Solved
Where is 2FA? Where is passkey?
The minimum expectation for account security on any random web forum is a TOTP based second factor, but this is no random web forum. Just about every instance of the popular forum platform Discourse and many others offer modern account security and work well with 1Password.
It's no fun having your customers second-guess you choices of technology partners, but while something like the lack of dark mode is an example of a disappointing failure, this is almost unbelievable.