AirPods pro keep disconnecting/reconnecting during phone calls only

Doesn't happen if listening to music/watching video. Only happens during phone calls.

I've tried staying far away from other devices so as to not have bluetooth interference.

AirPods are fully charged.

I've tried forgetting and then reconnecting the airpods to the phone (iphone 7plus)

This only became an issue four days ago. Never had problems prior to that.

Could it be some weird microphone issue?

BTW I can use for Zoom meetings on my HP laptop - no connectivity probs there.