If you need to step away from the meeting for a moment, you can turn on the "Do not disturb" mode. To do this, you can hover your cursor over your bubble or click on your avatar in the top right corner of the screen.
When you turn on the "Do not disturb" mode, your avatar will appear smaller to others in the meeting, and the message "Sorry, I'm currently away" along with the "Zzz" icon will appear next to your name in the list of participants on the right side of the screen. This lets others know that you are temporarily unavailable.
And you will see a "Do not disturb" window with an "I'm back" button to exit this mode.