The worst I've seen have uncommunicated password length maximums—but don't error when you exceed them. Instead, they just truncate your password, but only on creation. When authenticating, they don't truncate, so your password you just made with a password manager is "wrong".
Spotify did/does this. Made canceling my free trial really tricky, because I needed to log in again to do so.
Spotify did/does this. Made canceling my free trial really tricky, because I needed to log in again to do so.