Run the check
Watch the preview while moving a clock or hand through the frame.
Repeat after closing other camera apps, then compare another browser.
Try another port for an external camera and note whether the system reconnects.
Read the result
A frozen preview with an active stream points to delivery or app processing, not denial.
Limits and next step
The page cannot inspect camera firmware or another program's internal queue.
Repeat the check after changing one setting or connection. Keep a record of what changed before deciding whether the device needs service.