I use teams for work and have not had a single problem in the almost three years I’ve been with the company. We have teams phones and pretty much all teams licensing. I’ve had lots of problems with zoom and go to meeting. Especially with GoToMeeting when I was managing a citrix environment.
If they are making it past your firewall and hitting your computer then the firewall is open and it shouldn’t be. Or that’s an outbound connection triggering the alert.