Macbook 15,1 frequently crashes during video chat. How can I debug this?

The most useful info from the crash report is simply that it is not your main macOS system that crashed. It is the bridgeOS running on your T2 chip that has crashed. The T2 on your system is, amongst other things, responsible for image processing for the integrated camera.

Therefore it does not seem that looking into the GPU, integrated graphics switching or similar will have an effect on the problem. This seems very likely to be an Apple bug, which will be hard to avoid triggering. In other words - you'll need to downgrade/upgrade the OS on the T2 to get this fixed.

I would advise reaching out to Apple to report the matter, and hope for a speedy upgrade from them that fixes this.

This problem disappeared after some OS update (within the same major OS version, I'm still on 10.14.6). So in case anyone still experiences this, try to install all updates.