Apple Hide My Email bug, possibly related to disclosure vulnerability

Last week a disclosure vulnerability in Apple’s Hide My Email feature was publicly announced and verified by a news media outlet, though the technical details of the vulnerability were not publicized. The vulnerability is that it’s possible to unhide the real email address of a Hide My Email user. I don’t know whether I’ve accidentally stumbled upon that vulnerability, or perhaps in this case the Hide My Email user just messed up in some way, but I’ve definitely discovered a bizarre and troubling Hide My Email bug in Mail app (on macOS Sequoia 15.7.7). I received a support email for one of my apps to a published @underpassapp.com address. This happens practically every day. Bizarrely, however, Mail app displayed an alert that I’ve never seen before, “This message was forwarded to you by Hide My Email,” despite the fact that I have previously received many emails from people using Hide My Email. Clicking the Settings button opens…