Webcam Logitech QuickCam Pro 500 (ID 046d:08ce) is not working on my desktop with:
Operating System: Kubuntu 20.04
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8
Kernel Version: 5.13.0-25-generic
OS Type: 64-bit
Processors: 12 × Intel® Core™ i5-10400F CPU @ 2.90GHz
Memory: 15,5 GiB of RAM

Actually, computer correctly identifies it:
/win/research/2022/8B/2minus/program>lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 046d:08ce Logitech, Inc. QuickCam Pro 5000
Bus 001 Device 003: ID 04d9:1702 Holtek Semiconductor, Inc. Keyboard LKS02
Bus 001 Device 002: ID 045e:0084 Microsoft Corp. Basic Optical Mouse
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

But it does not work in zoom

I plugged the webcam into USB-2 port instead of USB-3 and suddenly the camera becomes live. It appears in SKYPE, but still I cannot see it in ZOOM.

This issue appears to other webcams too, e. g. konftel CAM10 & CAM20 and it's not limited to Linux.

How do you join to Zoom webmeetings? If you use a browser access to camera (& microphone) must be allowed.

I start ZOOM as a separate application. When starting it from Firefox, I have the same problem.
I noticed one strange thing: to activate the webcam in SKYPE, I need to unplug it from USB-port and plug-in again.

unplugging and plugging in.....suggests your distro has an usb suspend issue?
https://unix.stackexchange.com/quest...-7-10-or-above