Garrett,
When we marked the Protected Audience API as deprecated, in crrev.com/1545185, this included more of the API surface into the “Fledge” Blink use counter. You can see we added “DeprecateAs=Fledge” to a lot of the APIs in navigator_auction.idl in that change. It wasn’t actually an increase in API usage, it was just a change in measurement. You can see there were no corresponding spikes in particular API usage: https://chromestatus.com/metrics/feature/timeline/popularity/3855 https://chromestatus.com/metrics/feature/timeline/popularity/3857 On Tuesday, July 14, 2026 at 10:50:58 AM UTC-4 Garrett Johnson wrote: > I'm a researcher in this space who has ongoing research > <https://ssrn.com/abstract=4983927> measuring the adoption and use of > Privacy Sandbox tools. > > I'm hoping that someone in this chain could resolve a mystery for me about > the Fledge usage metrics in the Chrome Platform Status data here > <https://chromestatus.com/metrics/feature/timeline/popularity/4188>. > Basically, this approaches 0% of page loads in Q4 2025 as you would expect > given its retirement. However, usage spikes to its highest ever usage in Q1 > 2026 (peaking at 7.7%). This is unexpected: as mentioned above, auctions & > interest group activity has gone to almost 0 in the Chrome Platform Status > data (and my own). My guess is that some deprecation flag is being counted > here, but I really don't know. Other researchers > <https://arxiv.org/abs/2606.26390> found a similar spike in the HTTP > Archive data. > > I'd really appreciate your input here in setting the record straight on > whether PA API's post-retirement was in fact a mirage. Big bonus points if > you can explain why this happened. > > Sincerely, > > Garrett Johnson > Associate Professor > Questrom School of Business > Boston University > https://garjoh.com > > On Wednesday, 1 July 2026 at 14:25:39 UTC-4 Daniel Bratell wrote: > >> LGTM3 for steps 2 and 3. >> >> /Daniel >> On 2026-06-25 19:05, Chris Harrelson wrote: >> > LGTM2 >> >> On Thu, Jun 25, 2026 at 9:56 AM Yoav Weiss (@Shopify) < >> [email protected]> wrote: >> >> LGTM1 >>> >>> On Fri, Jun 12, 2026 at 2:32 AM Paul Jensen <[email protected]> >>> wrote: >>> >> Hi API Owners, Protected Audience API was deprecated in Chrome-144 with >>>> a plan to remove it in Chrome-150. Currently the usage is 1.1% of page >>>> loads. >>>> <https://chromestatus.com/metrics/feature/timeline/popularity/4188>We >>>> are proposing the following as next steps for removal and associated >>>> timelines: 1. M150: Remove all Ads API-related entries from Chrome >>>> settings and UI surfaces (e.g., chrome://settings/adPrivacy) via field >>>> trial. After this point, all API invocations for field-trial enabled >>>> browsers will always reject. Since the API can already be disabled for one >>>> of many reasons, scripts must already handle such rejections (or they’re >>>> already significantly broken). 2. M152: Permanently remove the >>>> underlying implementation code for the API, and replace it with a >>>> lightweight stub API. The stub will remain removable via field trial. >>>> >>>> 3. M152 Canary/Beta: Begin a controlled rollout of the stub API removal >>>> via a field trial. 4. M152 Stable: Assuming there are no regressions >>>> or breakage after reaching 1% stable, we will request additional approval >>>> for full removal at this stage. >>>> >>>> At this time, we are seeking LGTMs for steps #2 and #3. >>>> >>>> Thanks, >>>> >>>> Paul >>>> >>>> On Wed, Nov 12, 2025 at 11:30 AM Vladimir Levin <[email protected]> >>>> wrote: >>>> >>> LGTM2 >>>>> >>>>> On Wednesday, November 12, 2025 at 11:30:32 AM UTC-5 Chris Harrelson >>>>> wrote: >>>>> >>>> LGTM1 >>>>>> >>>>>> On Fri, Nov 7, 2025 at 11:04 AM Paul Jensen <[email protected]> >>>>>> wrote: >>>>>> >>>>> Intent to Deprecate and Remove: Protected Audience >>>>>>> Contact emails >>>>>>> >>>>>> [email protected] >>>>>>> >>>>>> >>>>>>> Explainer >>>>>>> >>>>>>> https://github.com/WICG/turtledove/blob/main/FLEDGE.md >>>>>>> >>>>>>> Specification >>>>>>> >>>>>>> https://wicg.github.io/turtledove/ >>>>>>> >>>>>>> Summary The Protected Audience API provides a method of >>>>>>> interest-group advertising without third-party cookies or user tracking >>>>>>> across sites. >>>>>>> >>>>>>> Following Chrome's announcement >>>>>>> <https://privacysandbox.com/news/privacy-sandbox-next-steps/> that >>>>>>> the current approach to third-party cookies will be maintained, we are >>>>>>> now >>>>>>> planning to deprecate and remove >>>>>>> <https://privacysandbox.com/news/update-on-plans-for-privacy-sandbox-technologies/> >>>>>>> >>>>>>> the Protected Audience API (along with certain other Privacy Sandbox >>>>>>> APIs, >>>>>>> as outlined on the Privacy Sandbox feature status page >>>>>>> <https://privacysandbox.google.com/overview/status>). >>>>>>> >>>>>>> Blink component >>>>>>> >>>>>>> Blink>InterestGroups >>>>>>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EInterestGroups%22> >>>>>>> >>>>>>> Web Feature ID >>>>>>> >>>>>>> None >>>>>>> >>>>>>> Motivation >>>>>>> >>>>>>> Chrome has announced that the current approach to third-party >>>>>>> cookies will be maintained. Since that announcement there has been >>>>>>> virtually no interest in the Protected Audience API. Use of the >>>>>>> joinAdInterestGroup() API >>>>>>> <https://chromestatus.com/metrics/feature/timeline/popularity/3855> >>>>>>> has decreased by almost 100x and use of the runAdAuction() API >>>>>>> <https://chromestatus.com/metrics/feature/timeline/popularity/3857> >>>>>>> has decreased by more than 10x. Of the auctions occurring today, >>>>>>> virtually >>>>>>> none of them have winners (determined by looking at the “Success” >>>>>>> bucket >>>>>>> count of the Ads.InterestGroup.Auction.Result UMA), implying that they >>>>>>> are >>>>>>> not providing useful benefit to the pages initiating them. >>>>>>> >>>>>>> Initial public proposal >>>>>>> >>>>>>> >>>>>>> https://privacysandbox.com/news/update-on-plans-for-privacy-sandbox-technologies/ >>>>>>> . >>>>>>> >>>>>>> Developer-facing impact >>>>>>> >>>>>>> Given that virtually none of the Protected Audience auctions >>>>>>> occurring today have winners, we estimate the lost utility from this >>>>>>> removal to be negligible. >>>>>>> >>>>>>> User-facing risks >>>>>>> >>>>>>> The user-facing risks are small. While removing the JavaScript API >>>>>>> could cause pages to break, the impact should be limited to sites that >>>>>>> don't employ standard defensive coding or feature detection, which >>>>>>> should >>>>>>> be rare since not all browsers implement the API. >>>>>>> >>>>>>> If usage warrants, we will take steps to avoid any risk of page >>>>>>> breakage, e.g. by temporarily retaining a stub implementation of >>>>>>> Navigator >>>>>>> APIs joinAdInterestGroup(), runAdAuction(), leaveAdInterestGroup(), >>>>>>> clearOriginJoinedAdInterestGroups(), getInterestGroupAdAuctionData(), >>>>>>> canLoadAdAuctionFencedFrame(), createAuctionNonce(), >>>>>>> updateAdInterestGroups(), protectedAudience.queryFeatureSupport(), >>>>>>> deprecatedReplaceInURN(), deprecatedURNtoURL(), and >>>>>>> adAuctionComponents() >>>>>>> that mimic current behavior when a user has disabled Protected Audience. >>>>>>> >>>>>>> Estimated milestones >>>>>>> >>>>>>> Planning to deprecate in M144 and remove in M150. >>>>>>> >>>>>>> Currently 0.22% >>>>>>> <https://chromestatus.com/metrics/feature/timeline/popularity/4188> >>>>>>> of page loads use the Protected Audience API. These are driven by a >>>>>>> small >>>>>>> number of third-party ad tech scripts present on a large number of >>>>>>> sites. >>>>>>> We will continue to monitor usage as well as provide comprehensive >>>>>>> updates >>>>>>> on privacysandbox.google.com with the status of the API and >>>>>>> deprecation plans >>>>>>> <https://privacysandbox.google.com/overview/status>. >>>>>>> >>>>>>> We will also proactively work toward reducing usage to low levels >>>>>>> once this intent is approved, including disallowing any new enrollment >>>>>>> sign-ups, and contacting enrolled sites to inform them about the >>>>>>> deprecation timelines. >>>>>>> >>>>>>> Protected Audience features that were never launched beyond 20% >>>>>>> Stable (TextEncoder support >>>>>>> <https://github.com/WICG/turtledove/issues/961#issuecomment-2793763963>, >>>>>>> >>>>>>> Creative scanning via BYOS/V1 trusted scoring signals >>>>>>> <https://groups.google.com/a/chromium.org/g/blink-dev/c/EXfp34Qb1oc/m/oaiY6MENBwAJ>, >>>>>>> >>>>>>> Selectable Reporting IDs >>>>>>> <https://groups.google.com/a/chromium.org/g/blink-dev/c/1cWqBPHngd0/m/gSYeR_dPAAAJ>) >>>>>>> >>>>>>> will be ramped down by the end of 2025. >>>>>>> >>>>>>> Protected Audience services, Bidding and Auction services >>>>>>> <https://groups.google.com/a/chromium.org/g/blink-dev/c/CyXJz3xOEcc/m/1snkv2KhAwAJ> >>>>>>> >>>>>>> and Trusted Key Value service >>>>>>> <https://groups.google.com/a/chromium.org/g/blink-dev/c/fH8u7ZTNZg8/m/oo0WVw7SAQAJ>, >>>>>>> >>>>>>> will not onboard new clients once deprecation is approved. We will work >>>>>>> with onboarded clients and plan to turn down the services by the end of >>>>>>> year as usage is negligible today. This will have no user-facing or >>>>>>> web-compat impact. >>>>>>> >>>>>>> Link to entry on the Chrome Platform Status >>>>>>> >>>>>>> https://chromestatus.com/feature/6552486106234880 >>>>>>> >>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "blink-dev" group. >>>>>>> >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>> send an email to [email protected]. >>>>>> >>>>>> >>>>>>> To view this discussion visit >>>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABQTWrnevtY14OMos%2BuDgzXtFwQJ5vzY3hEMmyRFQBKDHBz-9A%40mail.gmail.com >>>>>>> >>>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABQTWrnevtY14OMos%2BuDgzXtFwQJ5vzY3hEMmyRFQBKDHBz-9A%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>>>> . >>>>>>> >>>>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "blink-dev" group. >>>> >>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>> >>> >>>> To view this discussion visit >>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABQTWrmRRxZO%3D%2BCmt-hfkBBjeR8j4umTer8krMvmAyiVP_1HXw%40mail.gmail.com >>>> >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABQTWrmRRxZO%3D%2BCmt-hfkBBjeR8j4umTer8krMvmAyiVP_1HXw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "blink-dev" group. >>> >> To unsubscribe from this group and stop receiving emails from it, send an >>> email to [email protected]. >> >> >>> To view this discussion visit >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohS%2BRQAUtSUZw%3D4TsVgNOxcuR5aeQhym2CZO-_WmzUnndLQ%40mail.gmail.com >>> >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohS%2BRQAUtSUZw%3D4TsVgNOxcuR5aeQhym2CZO-_WmzUnndLQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> >> To view this discussion visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw94fqnFNWSUWQSm7crPrzuLbO6Cz5p9Rg0BLEJsU%3DHPPg%40mail.gmail.com >> >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw94fqnFNWSUWQSm7crPrzuLbO6Cz5p9Rg0BLEJsU%3DHPPg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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