"Your screen is being observed" message - wtf?

[TR888]

I've just walked into my home office and Naren a "Your screen is being observed" message on my screen. I use a Mac, in case it matters.

What does it mean?! And what do I do?

Just googled the message, it seems to be a thing - maybe related to having screen sharing switched on or something.

Look it up for info how to sort, doesn't look dodgy.

Is it IT equipment provided by your company?

Hm. I'm not sharing my screen with anybody... I've restarted the computer, let's see if the message is still there.

No, it's my own computer.