- Allow you to paste passwords into their smartphone app, but not into their web site being accessed from the same device.
- When entering new passwords, limit the password length but not tell you what the limit is ("password is too long"), so you have to reduce it 1 character at a time and keep trying.
- (Mentioned elsewhere in this post) Limit the special characters to some inexplicable subset like !@#$, so you have to edit your generated random password and replace the non-compliant characters with ones from their subset.
- Limit password lengths to (say) 20 characters, allow you to enter a new 20 character password, but only store the first 19 characters so you get an invalid password error when you subsequently log in! I figured it out because I knew I was pasting the correct password, so I just thought, "Hmm, UI team != DB team..." and tried one less character. Bingo.
This happened to me with an old version of (IIRC) a Bank of America iOS online banking app (I am not concerned about mentioning a name here because it's been fixed since then).
- Limit your password to something really short like 10 alphanumerics.
- Require password entry for (say) iCloud before you can get into your password manager, forcing you either to pull up the password on another device and painstakingly enter by hand a 30 character random string, including many special characters, and not letting you see the password (only the last character, for a second). This is so unpleasant that I am sure many people would just change the password to their dog's name or something.