Hi,
I also have WH1000XM5 headset, the first time I connected them to my PC (W11) I could use the headset without a problem. The second meeting I had that day I started having the issues described in the thread.
Not sure if this happened to you, but when it was not working, by doing a test call in Teams I hear the first "beep" when the call is recording your voice, but it never play back the recording, it just tells me that if Im satisfied with the audio everything was ok.
I has this issue for some time and what I did that at least fixed it for me was to connect the headset to my phone and initialized the headset, which I believe is to restore it to its default settings, I paired them again in my phone, I removed the device from my PC and paired them again. After that, the test call was working fine and I could hear myself in the recording.
Hope this works for the rest of you :)