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.
Think of it from a random guess perspective. Guessing a number randomly generated between 0-16 is easier than guessing one between 0-8.
Now think that all passwords are stored in certain amount of bits, so let’s compare 4 and 8 bits.
Each bit has a chance to be either 0 or 1, so guessing a single bit’s possibility is 1/2.
Guessing the correct orientation of 4 different bits takes 1/24 = 1/16
Guessing the correct orientation of 8 different bits takes 1/28 = 1/256
Now think passwords being stored in more bits(=longer password)
At a certain point it doesn’t matter as the password is effectively unguessable.
One weakness with longer passwords is that if they are created by humans chances are it will be easier to guess the pattern. This is true for all human created passwords but I think the longer ones are worse since there is more space to create a easily guessable pattern.