Using `guix weather`, we can check substitute availability for the staging branch:
------ master branch aarch64: 66% x86_64: 93% i686: 85% armhf: 51% staging branch aarch64: 44% x86_64: 80% i686: 60% armhf: 30% ------ So, substitute availability is definitely lower on the staging branch. It's not clear if this is the result of "real problems" with the packages or problems with the build farm.
