Just saw that rc3 was released so I updated to that and it still didn't work.Try the new 26.0.0 rc2, maybe that one already has improve..
It's a bug with CEF (browser sources). If you have any browser sources anywhere in your scene, even if they are disabled, OBS will crash. There is no current workaround
macOS Big Sur Known Issues (caused by CEF + Audio Monitoring) · Issue #3095 · obsproject/obs-studio
Nothing surprising, but I hope this report can help to make OBS available on the new macOS as soon as it's get's released. Once you starts OBS on Big Sur, it's quit unexpectedly, here's the trace: ...github.com
Grabbing a browser window will work around some use cases.The only current workaround is to revert to Catalina or earlier.