128 characters is the maximum my password manager (Bitwarden) offers. I chose this option to see what would happen.

I just signed up to check out this forum. During the registration process, I attempted to use a 128-character password, but it seems that the text string I entered was silently truncated to 30 characters.

For a future version of YaBB, I think it would be good to have an indication of the maximum allowable password length at the time of registration or changing one's password. A longer maximum password length might also be desirable.

As it turns out, when attempting to log in, pasting in the full 128-character password I had intended to use did in fact work. It was presumably pruned to 30 characters during login as well as during registration.