Phone call issues on air pod pro gen 1

I've all along had the issue that my AirPod pros gen 1 will start breaking up while I'm on the phone. I know it's not the connection because when I switch to the iPhone speaker it's fine. Randomly I'll be on the phone and the audio will start going in and out. The only fix I've noticed is I switch the call to speaker for about 30 seconds and what I switch back to the AirPods it works again. It’s getting frustrating. All other Bluetooth features work flawlessly. It’s ONLY when I’m on a phone call. I’ve done everything. On the phone multiple times with TMobile and Apple tech support. Been to Apple store twice. Restored my phone from a file on the Genius computer and lost all my apps. A It’s on iPhone 13 Pro. I am in the midst of sending the phone in for repair. When I received the loaner phone from Apple (same phone as mine) I had the exact problem on my first call! What is going on?? Help!