This is in all likelihood not actually caused by an OctoPrint upgrade. The reason for that is simple: OctoPrint has no idea what a webcam is. It only accesses and embeds certain HTTP endpoints to take snapshots or display a feed and doesn't interface with the camera directly in any shape or form.
If your webcam "no longer works" after an OctoPrint upgrade, the likely causes based on our experiences here are
You've been ignoring an undervoltage issue for too long and now your system is finally unstable enough to cause you issues like devices attached directly to it no longer working correctly. Fix any observed undervoltage or overheating problems immediately. We are not joking about this.
Some third party plugin is actually interfacing directly with the camera or its configuration in some shape or form and that has now caused some issues. Try safe mode.
Only if that doesn't work open a support request, in #support:support-webcams. Be sure to include a systeminfo bundle and
/var/log/webcamd.logat the very least and also clarify in what way the webcam no longer works! Does it still light up but there's no picture in the web interface or does it not even show any activity anymore? Does it work when directly accessing the stream URL? Does only the stream not work or only the snapshot or both? We'll then see what we can do to help you.
It was mere coincidence and the issue lies with the camera, the webcam server or something else entirely.
Please stop blaming OctoPrint upgrades on everything that goes wrong with your whole electronics zoo. Read the changelog, test in safe mode, be forthcoming with logs. Thank you.