In this case it looks their work is based on another branch not yet merged (https://github.com/obsproject/obs-studio/pull/5155 which adds support for Apple Silicon) - and the commit is from there.
https://github.com/obsproject/obs-studio/pull/5875#issuecomm...
And it looks like they're just going to set the PR to a draft until after 5155 is merged, so it will get cleaned up and be easier to review then:
https://github.com/obsproject/obs-studio/pull/5875#issuecomm...
HN is usually better about sussing out the real story.
This happens with every transition in Apple history. It takes pulling the rug out completely before many devs will do it
Look at the Python transition, the carbon to cocoa transition, even the original Rosetta transition.