Searching for Presenter Mode

Hello everyone,
I’m looking for the presenter mode like https://jitsi.org/blog/introducing-presenter-mode/
Where is the setting?
Greetings

Just start sharing your screen and turn on your camera.

When I do that, it shows at the bottom that the camera is on.
But the camera image on the presentation is missing

What browser and version are you using? For sure it works with latest chrome …

I have tested different browsers. I usually use Opera or Firefox.
Is there somewhere a setting to change the size of the camera-field? And where can I adjust its position?
Hopefully I find the problem there…

There are no such options. Try it with chrome.

It doesn’t work with chrome…