Looking at the changes between 2.11.0rc1 and 2.11 there is nothing indicating that compatibility should break:
https://github.com/metabrainz/picard/compare/release-2.11.0rc1...release-2.11
Attached are the build logs from building 2.11.0rc1 (https://github.com/metabrainz/picard/actions/runs/7486957675/job/20378362828) and 2.11 (https://github.com/metabrainz/picard/actions/runs/7653162616/job/20854436648). I have removed the timestamps, so the files can be diffed.
There are no essential differences in most of the build. But what might be related is an update to the Github runner image. On the 2.11.0rc1 build:
On the 2.11 build:
Other relevant components, most significantly Python, PyInstaller and Qt5, are using the same versions as before. MACOSX_DEPLOYMENT_TARGET is set to 10.12.
It all indicates we might finally have come to and end where we are no longer able to provide 10.12 compatible builds using Github actions. Which means we will drop these for future releases. This is the case for Picard 3 already anyway, but the hope was to continue providing builds for 2.x as long as possible.
We could do a final 2.11.1 release and provide custom builds manually created on macOS 10.12. But this would be a one time thing. If we cannot automate the build this is not a maintainable option.
Latest builds from CI runs work again on macOS 10.12. E.g. from https://github.com/metabrainz/picard/actions/runs/8318407367
Again nothing relevant changed in the Picard sources. So it most likely was some change to the runner images. That means we should be able to do a fresh release to fix the issue.