In password security, the longer the better. With a password manager, using more than 24 characters is simple. Unless, of course, the secure password is not accepted due to its length. (In this case, through STOVE.)
Possibly indicating cleartext storage of a limited field (which is an absolute no-go), or suboptimal or lacking security practices.
Common mistake for amateurs that found a password library and used it without reading the documentation. E. g. bcrypt will tell you to salt and hash the password before digesting it into constant length output for your database.
Salting before doing anything else is basic password security. I assume the webpage in question doesn’t do that, either.