Microsoft and your ISP probably peer directly at your nearest IX. This means that a packet between your house and Microsoft would never traverse the "public" internet. It would go on your ISP's network to the IX, then directly to a Microsoft router, then ride Microsoft's network to the data center Teams is hoster at.
One possibility is that something happened at that connection at the IX. For example the transceiver (laser) on your ISP's router went out, and there is a bug in their processes or management code that is causing the BGP route to stay up even though it is really down. In there case traffic would keep flowing to that broken port and then just die there. Instead it should have switched to a redundant router or the ISP's router should have redirected all traffic to Microsoft over another part of the internet.
You can use the publicly available PeeringDB database to look up Microsoft's ASN (8075) and see what IXes (Internet Exchanges, basically a big building with a bunch of cages for rent where all the global and local internet players will have routers that peer with each other) Microsoft has a presence at: https://www.peeringdb.com/net/694
