The feature which shows you what position a letter is in a password is currently only present in the passwords field and not for hidden custom fields.
I would like to see this feature added to the hidden custom fields as well as passwords. I recently encountered a UK bank (a familiar character in the story of this feature) who want specific characters from the ‘answer to a memorable question’.
It was merged for the password field in this PR as a contribution from @mkanavakatini