/r:
UN officials, world leaders, and high-ranking dignitaries cover their phone cameras primarily as a failsafe protection against zero-click spyware, remote activation, and accidental data leaks.
While software fixes and encrypted apps protect data in transit, they cannot override the laws of physics: if a camera lens is physically blocked, it cannot see, no matter how sophisticated a hacker's exploit is.
Time warp 2016: "Mark Zuckerberg masks Mac webcam and microphone"
https://www.bbc.com/news/technology-36596070