I was unable to find any documentation or open GitLab issues with Tor regarding the need to take additional steps before security settings are fully applied
some (not all) of the prefs in the slider require a restart, so it depends on the state of those prefs when you open the browser as to what you actually get in terms of security: it is a security slider. Some prefs that require a restart and some slider prefs that don’t are fingerprintable.
And not only are we adding entropy that wasn’t designed for, but we’re misleading users as to their security. We could solve this by forcing a restart but that then becomes a pain point
As shared by @any1.
There still really ought to be a warning and documentation, but there is an issue on GitLab.