

Really sorry, it’s too long ago to remember the exact error,
but IIRC
when you followed the ubuntu instructions for adding the repository it would kick an error because the command included a reference to noble and mint os name is xia so the contents of the osrelease when checked didnt match and it threw an error.
Could be wrong, I didnt document it.
The work around was to edit the commands.
All a moot point now as
a) the instructions now on the mullvad site don’t reference noble and
b) mullvad now appears to be in the mint store (which is how you should always install if possible
Depends on your settings. Firefox has a setting for delete cookies on exit. It is not on by default though