Total Cookie Protection makes a limited exception for cross-site cookies when they are needed for non-tracking purposes, such as those used by popular third-party login providers. Only when Total Cookie Protection detects that you intend to use a provider, will it give that provider permission to use a cross-site cookie specifically for the site you’re currently visiting. Such momentary exceptions allow for strong privacy protection without affecting your browsing experience.
The latest version of Firefox will now silo most cookies to only be usable by the domain that created them.
If you aren’t using Firefox or Safari (perhaps Brave? I don’t know enough about it to recommend it) you should really reconsider. If you’re still using Chrome in 2021 you might just be out of your mind. No offense, of course.