Microsoft teams user agent
Solution 1:
I also had this question because I wanted to block link unfurling from MS Teams for an app I was developing.
I used the following line from in a Flask app
request.user_agent.string
To get this user agent
Mozilla/5.0 (Windows NT 6.1; WOW64) SkypeUriPreview Preview/0.5
This was January 2020 so it may change over time, FYI