We have been made aware of an issue with recent versions of Raspberry Pi OS which cause crashes when using a USB webcam with Zoom on a Raspberry Pi.
We understand that Raspberry Pi are aware of the issue and will be looking to resolve this in a future Raspberry Pi OS release (date unknown). The issue is being tracked here and elsewhere: https://github.com/raspberrypi/firmware/issues/1546. Using an older version of Raspberry Pi OS is a suggested temporary workaround here.
There is also a forum post that has identified this issue, which shows additional workarounds by using a USB audio device: https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=306408