Hello Branden, thank you very much for your helpful emails and detailed analysis!
I came across .output command in NixOS' site.tmac, but did not think much of it at the time and it certainly eluded me when thinking about the man-db test failures observed on the PR¹. It seems the conversation on the PR now needs to be around what the default output format for manpages on NixOS should be default, i.e. SGR and OSC enabled vs legacy, i.e. SGR and OSC shut off. This is likely going to be an interesting conversation. Happy to report back once there is a path forward. Thanks again! Alexis ¹ https://github.com/NixOS/nixpkgs/pull/241870
