Hey again! Reinstalling the OS doesn’t, it just over writes the existing operating system with a fresh copy, your files aren’t touched. Still always a good idea to backup before doing so.
However, if the issue doesn’t occur in a new admin user, a Reinstall of the OS probably won’t fix the problem.
If it’s an issue with a specific user account, most likely the problem is with a setting/preference, software installed or launching solely on the user account, such as a Login Item. (System Preferences > Users and Groups > Login Items, if you see any there, a good step is to remove them and restart to test). Or the problem is with the user account permissions, which can be reset as well, which, many times solves user account issue. For Big Sur though, this step, besides a few others beforehand, also requires a Reinstall of the OS.
Otherwise, there are a few directions you can go to move the data to the new user account, without the possible corrupted files/directories, which isn’t too bad of a process, as there are mainly a few folders with the data to transfer:
Desktop Documents Pictures Music Movies Downloads, and any cloud service folders, such as One Drive, Dropbox, etc.
Likewise, if you already have your data stored in iCloud, for the most part, it’s as simple as just signing into your account, and enabling all the iCloud features. (Or other provider’s cloud data, as said before).
Hope that helps some!