Only one person is picked up by iphone micrphone when 2 are talking

Hi,

I noticed that when I have a video call (using facebook messenger or google meet) where two people are in front of one iphone, only one can be heard clearly. The other person's voice is canceled out.

We talked in a 2x2 setup (two iphones connected, two people in front of each iPhone). Speaker 1 (phone 1) spoke for some time. After that, speaker 2 (phone 1) started talking, but nobody could hear her. The same thing happened later. After speaker 3 (phone 2) spoke for some time and speaker 4 (phone 2) wanted to talk he couldn't be heard on phone 1. In both these cases, 'privileged' speakers (1 and 3) had to repeat what the other speaker, sitting right next to the 'canceled' speaker had just said. This was heard with no problems.

I heard about the voice isolation feature, but I never turned it on. I'm using iphone 13 Pro 16.3.1

What can be done about it?