I've tried it today and yeah, 1-to-1 calls magically/unsurprisingly start working. In fact, the whole UI gets a facelift and lots of new features.

If I had to guess, I'd say Microsoft keeps around a version of their UI, which hasn't been maintained in over a year, and serves that to anyone initiating communication with a user-agent string they don't like.

If that's true, that's a massive security vulnerability. Admittedly, also unsurprising for Microsoft. @xavier666@lemm.ee