Logitech C920 webcam freezes on Mac Pro with Big Sur V11.4

Could someone help me to get my webcam working?

Prior to V11.4 of Big Sur, my Logitech C920 webcam worked flawlessly for Zoom and FaceTime on my Mac Pro (Intel processor). After I upgraded to Big Sur 11.4 the camera now freezes almost immediately on starting either application (sometimes it continues to provide images where the frame jumps and other faults make it useless).

Alternatively is there a webcam for Zoom/FaceTime that works under V11.4?

Thanks for your help.