> the identifier can also persist [...] as long as the Firefox process remains running
Make sure to exit Tor Browser at the end of a session. Make sure not to mix two uses in one session.
Use a separate machine for these stuff, never mix your clean machines with the dirty ones, complete separation, different networks
the vulnerability was fixed upstream by mozilla anyway
better yet, disable javascript when using tor.
Or shut down and boot tails again. You need privacy? Take your time.