C:\Users\ “name of the user account” \AppData\Local\BraveSoftware\Brave-Browser\User Data\Default
In that sub-directory, there is a file named “Top Sites” - it’s a SQLIte database file. Ensure there’s no permissions issue …
Right-click on the file (need to quit Brave first) and select Properties.
On the General tab, ensure “Read only” is not checked.
Select the Security tab and for your user account, ensure Full Control, Modify, Read & execute, Read, and Write are checked for Allow column.
And double-check “who” owns the file … for example, if it’s “Administrator”, and you’re logged in not as Administrator (shouldn’t be!), that may be the issue.