suddenly won't save files

All of a sudden I’m unable to save any new files on my MacBook. What would cause this problem? I already have security setting to allow full disk access.

More information required. Like what error message do you get. What happened since the last time you could save files. Etc.

… updated to Big Sur, which LibreOffice version? Does: sudo xattr -d /Applications/ fix the issue (to be executed in Terminal)?