Normally I'd cry foul but 20 alphanumeric characters (roughly 64^20, or 1e36 combinations) is more than sufficient.
Granted it's possible they're limiting it to 20 for a nontechnical reason, but I have some 40-character passwords in a password manager. Long passwords are not only reasonable, but this is a giant alarm bell if they even imply they might be storing them insecurely.
I also find it a bit "armchair quarterbacky" to be calling out PayPal on security practices. They've been around the block a few times, and though I certainly don't love them, they aren't making rookie mistakes like not-hashing passwords or the like.
You are just spreading FUD for no discernable reason. 20 characters while not the epitome of greatness, isn't a sign of the end times.