I’ve been having a similar issue with the microphone. It worked for years like a… legend. Somewhere around 2017-2018 I started getting complaints that my voice was faint and distant when calling though my iPhone. When connected with my laptop via the UC dongle my voice is clear as ever for all major videoconferencing software (on Windows). Switch to a my iPhone(s) it’s crap. For some time I stuck tape on the third microphone that does the ANC. It worked for a while, untill it no longer did. I had a call today with a customer service agent who, surprisingly, was not working off a script. His recommendation was to change the headset language. This forces a complete flash of the firmware. Unfortunately there was no success and the problem is still there. What is so different between the connection with the UC dongle and the connection with an iPhone?