Hello everyone,
Few days back I started having same microphone issues with my Mi 10T Pro (MIUI-V13.0.12.0.SJDEUXM). Namely the microphone doesn't work when I'm making cellular phone calls, for google assistant and for two guitar tuner apps I've use (gString & waves). However the microphone works without any
problem for WhatsApp, Viber and when I'm recording sound.
Also doing phone call with my Huawei GT2 watch works and using Google Pixel Buds Pro, also Google assistant is working over Pixel Buds.
Restarting phone helps for a 30ish minutes, I've factory reset my phone as well and that also worked for 1-2 days, and now once again it stopped. The last update seem to messed things quite a bit, and I hope there will be solution from Xiaomi soon, because I was thinking of buying some newer Xiaomi model but after these issues I'm having second thoughts.