Interesting. I have never had echo but disconnected ANC right away without using phone and ANC at the same time. Certainly disconnecting ANC should not make phone audio worse as there are three microphones in the roof with at least one separate from the ANC (as far as I can tell).So I have the luxury of testing things on our pp's being the wife and I both have a 2021's. Since disconnecting my anc my echo phone issues have disappeared while the wife's echo issues are still there being hers have not been disconnected.
I will test this over the next few days by disconnecting hers as well. If nothing else the stereo will sound better as will the annoying fake piped in engine and exhaust be gone!
I will update this weekend being many has complained about phone echo`s while talking through Bluetooth.
My thoughts are the anc has many cons and many pros if disconnected!
I am not aware of any cons of disconnecting ANC unless the hum from variable cylinder management bothers you. I didn't really notice any significant road noise being removed beyond the low frequency engine noise when VCM is on, which isn't often.