I once registered an account with a random ~25 characters long password (Keepass PM) for buying tickets on https://uhuu.com.br/

The website allowed me to create the account just fine, but once I verified my e-mail, I couldn’t log into it due to there being a character limit ONLY IN THE LOGIN PASSWORD FIELD. Atrocious.

EDIT: btw, the character limit was 12

It’s much better performance wise now, but you better have a good internet connection because at the first sign of a dropped package the whole thing breaks down…