Citi can be a PITA with unlinking every few weeks for no apparent reason, but the app will tell you if it comes unlinked. My other accounts stay linked well. Our bank will unlink if we haven’t logged in online (to the bank’s site) in more than 30 days but that’s their rule, not YNAB’s rule, and it’s a good idea to log in to all your accounts monthly for a checkup anyway.