I would argue that this is not just banks but a number of different services. This entire Github repository [1] and this Twitter account [2] are dedicated to sites with dumb password rules. Passwords are not meant for humans.
Here is a link to a hackernews thread discussing the worst of the requirements in the repository is here [3].
The PayPal section doesn't mention that they have a 20 character limit too. I honestly wonder what kind of buffoons are in charge of making this shit up at multi-million dollar companies.