How I read it is that they’ve reintroduced it in FF 139 and that you need to enable the third-party certificates to acces the client certificate in the Android cert. store. But the linked bugs in the later replies of my link mention a regression in FF 140+.
I do agree that this is still a horrible UX though. Sadly I don’t have the time currently to test it.
I was curious so I looked it up… But it should technically work on FF for Android, although there is a bug in the UI.
See:
This is only true for the connection security. With mTLS you can also authenticate to the webapplication you’re trying to reach. So consider your use-case between vpn/mtls.
If you’re really out of options you can just brute-force it:
# grep -r 'old.home.lab' /etc
Or any other dir with configs…
That AI bot must be saturated with break-up and “Delete Facebook, hit the gym!” advice…