[PeterisP]

It's a Google issue no matter what. No matter what Microsoft did in their Teams app, the fact that it was (and still is!) possible is a critical flaw in Google code which Google has the duty to fix ASAP. The problem is not fixed until it is impossible for 911 calling to break even if the old Microsoft Teams app is used, and until emergency calling is certain to work even if someone else intentionally made a malicious app trying to hijack 911 in a similar manner.

I mean, that's literally a top priority without compromise - if it turns out that for some reason they can't implement third party dialing in a way that ensures proper handling of emergency calls even in the presence of buggy or even actively malicious third party apps, then an acceptable solution would be to kill all third party dialing; there is no permissible tradeoff whatsoever between features and emergency calling.