If you are making a character in a campaign where content sharing has been turned on, then any content owned by other people in the campaign will be usable. That may be what you're seeing. Also, in campaigns, homebrew content in any person's collection is shared, so if someone made a homebrew copy of a subclass, that might be the answer also.
some Tasha's content is being shown like pact of the talisman when I don't I make a character yet have the book. it isn't consistent though.
If you are making a character in a campaign where content sharing has been turned on, then any content owned by other people in the campaign will be usable. That may be what you're seeing. Also, in campaigns, homebrew content in any person's collection is shared, so if someone made a homebrew copy of a subclass, that might be the answer also.
Birgit | Shifter | Sorcerer | Dragonlords
Shayone | Hobgoblin | Sorcerer | Netherdeep
the only campaign I'm in is one with all new players and none of them own Tasha's. I also did not have homebrew on.