Once upon a time (see: 10 years ago), I created a Yahoo! ID that was not an email address. It was a string of characters. The email address behind it was a Gmail address.
I need to get into that account as it's the owner of a Yahoo! Group that I need to make changes to, but I can't - it doesn't seem to be possible to sign in by non-email ID, nor does it seem possible to sign in with a Gmail address.
Has Yahoo! completely removed these IDs from the platform? Am I toast?