What version of macOS and OBS are you using? Anyway, the problem then is related to the system extension installed in Library/SystemExtensions. To permanently remove it you need to restart the computer in recovery mode, (here
https://support.apple.com/en-us/HT201314 you can find the info for both macIntel and mac Silicon), temporarily disable SIP -System Integrity Protection-, (open terminal and type csrutil disable, enter username and password, wait a few seconds for the confirmation message and restart) then go into the /Library/SystemExtensions folder and delete the folder that contains the OBS Virtualcam extension. With that done, reboot into recovery mode and turn SIP back on (csrutil enable this time), then reboot normally again and you should have no more problems. If it asks you to reactivate any other extensions you may be using, follow the instructions and reactivate them. Hope this helps.