An invite link shows a preview of the tribe: its logo, name, category, description and how many members it has. Never who they are.
Signed in, the invite is redeemed straight away. Not a member yet? Sign up first; the invite is remembered and redeemed the first time you land on your dashboard. Some invites lead to a request to join instead, which the tribe's admins approve.
Invites sent to an email address expire after 14 days, and an invite bound to a specific address only works for that account. Tribe admins can regenerate their invite code at any time, which invalidates every earlier code and link. Joining or leaving twice is harmless; the second tap agrees with the first.