I have a 2nd monitor connected to my imac 27 inch 2020. It crashes my computer to the point where I cannot work with it unless I disconnect it . I have done further research and found that this is a major issue on Big Sur. The only solution to fix this is to go back to Catalina
Run software update to ensure you have the most up-to-date version of Big Sur. Then restart the computer in Safe Mode per the directions in How to use safe mode on your Mac - Apple Support and then restart normally and retest.
Run software update to ensure you have the most up-to-date version of Big Sur. Then restart the computer in Safe Mode per the directions in How to use safe mode on your Mac - Apple Support and then restart normally and retest.
Monitor Issues in Big Sur
