Ran into a strange issue where uploading files through Firefox would cause the whole system to freeze.
Firefox - 97.0.1 (64-bit)
Zorin - 16 / 64-bit / X11
Fix - in Firefox - Settings - Privacy & Security - Cookies and Site Data
Clear "Cookies and Site Data" & "Cached Web Content"
This is annoying as you'll have to log into websites again but this is the only fix I found that worked. There wasn't a lot of information on this issue so hopefully, this might save people time in the future.