FaceTime HD Camera Not Working

My in-built camera is suddenly not working on any of the apps (FaceTime, Zoom, Skype, Teams, etc.) on my MacBook Pro. I have latest updates on the OS (macOS Big Sur 11.5.1).

Referring to https://discussions.apple.com/thread/250288990 I have everything suggested on the discussion.

1. On different user account - camera not working
2. System Information shows

FaceTime HD Camera:

Model ID: Apple Camera VendorID_0x106B ProductID_0x1570

Unique ID: DJH63454JMYGJKD3G

3. SMC Reset - Done

4. Apple Diagnostics - Shows 'No Issues found. Reference Code : ADP000'

Please help me understand what might be going wrong with my in-built camera.