Taking out a camera to make a picture is pretty noticeable in a meeting with few participants. The standard way to use a phone camera involves lifting it pretty close to your eye level. Other participants could literally shout to please stop photographing the screen. It will be also very visible who was trying to do so.

Yes, somebody who's clever enough would keep the camera away from view, and maybe would try several times first to hold it in a way that gives a good view of the screen, etc. But this is out of scope, it's a clear malicious intent, when we could expect much more sophisticated means.