On a similar note in terms of frustration, my bank ended up getting me to memorize my randomly-generated passwords twice because it blocked pasting. I guess it's to discourage writing them down in plaintext files, but I bet it just makes most people choose meaningful (and therefore weak and guessable) passwords.
I once ran into a signup/login flow that allowed 36 characters in password when signing up but when logging in, the password field was limited to 20 characters.
I think I must have changed my password several times thinking I just copied it wrong or it had special characters that weren't allowed, but nope, the truth was somehow stupider than that.
