Having upgraded OBS before on macOS, I backed it up first, then installed the new version. As somewhat expected to me, the new version is not launching. I had to launch it from CLI to see and see there is an error:
error: os_dlopen(libpython3.9.dylib->libpython3.9.dylib): dlopen(libpython3.9.dylib, 257): image not found
It also changes something in the stored state on disk so that next time you try to launch an older version, it cannot launch either. So the issue damages the previous versions somehow as well.
Similar errors have happened to me in the past. If you are doing important streaming stuff, do not upgrade OBS as long as it continues to work. Especially if you are on a tight deadline or have a scheduled upcoming stream.
Maybe check with otool on macOS and check to see where it is looking for the .dylib it can’t find. You can also update the executable with otool to use a different path to the dylib, if need be.
Similar errors have happened to me in the past. If you are doing important streaming stuff, do not upgrade OBS as long as it continues to work. Especially if you are on a tight deadline or have a scheduled upcoming stream.