Correct me if I am wrong - please. When the computer is booted normally - the problem is there. When the computer is booted in Safe Mode - the problem is not there. Am I correct ??
A couple of thing could be happening. There is Third Party software interfering with the normal operation of the computer and Big Sur
And - there is a problem with the User Account.
First possible issue of third party software
Are there any AntiVirus, Disk Cleaner, Optimizers, Un-installers, etc installed which should be removed as per Developers Instructions. They are useless, unneeded, cause havoc and interfere with the normal operation of the OS and may even Corrupt the OS requiring a Reinstallation. The Built-in Security of Big Sur is all that is required.