Seems the FLAC maintainer hasn't got time/motivation to work on FLAC. He merged a bunch of PRs on March 15 2021, and his last commits before that are from May 14 2020. Someone else involved with Xiph/Mozilla has merged a few PRs, but the last activity (merging, commenting etc.) by anyone with write access to the FLAC repository has been well over 6 months ago.
Well that's a shame. Might be time for a fork.