Have has none of theses issues. Ran Big Sur and since upgraded to Monterey - and still no issues.
Has one attempted booting in Safe Mode and run that was to Test if the same issues are presented ?
This Mode will load slowly - normal.
It does a Repair Disk, clears cache files and Eliminates Third Party Software, extension and fonts from loading.
Should the issue described not be presented 1 - there is Third Party Software at play or 2 - something in the user account might be the cause.
To further isolate the issue Set up users, guests, and groups on Mac and then sign out of original account and not the newly added account the Test again
Should the issues not be present in newly created account - this would seem to indicate the original account is the source of you issue.