Hey!
Have you tried to launch (install) two separate versions? And what was after clean OBS reinstall?
Have You tried to check macOS Safe Mode?
Turn off your Mac -> Locate the left-hand side "Shift" button, press and hold it after the power button (or before; in case of USB keyboard) before Apple icon (or Ka-boom sound)
Run OBS from there. Yep, it might be laggy, but if OBS will handle tasks properly in Safe Mode, then at least we will have information that the problems are somewhere near macOS
Also, it might be some "bruh" with the newest Big Sur OS.
FYI: according to the log file....everything ok with audio devices (USB?)
If it is possible, disconnect all hubs, USB audio boards, etc.