For a very long time, Chase bank public websites only accepted the first 8 characters of your password. Anything else was silently dropped. If you used Chase for any loans, credit cards, or banking, you were forced to change your password around 2016ish, this is when they finally resolved this problem. Why? Mainframes.

Bank of America, internally, required you to have two passwords, a Windows and a UNIX password. The UNIX password was only 8 characters due to , you guessed it, mainframes. I don't know if this was ever resolved.