In addition to suppressing system notifications during a video conference or call (Quickly muting notifications while in a video conference) you can suppress Teams notifications also. These chat message previews and pop-ups can be annoying, especially if you happen to be hosting a meeting on your screen in a room when they arrive.
You have two options:
\uD83D\uDCD8 Turn off Notifications for all meetings and calls by default (on this computer)
Click on the more icon (… or three dots) at the upper right near your picture or initials to reveal more options
Click on the Settings option
On the Settings panel, click on Notifications (fourth on the list)
Click on the Edit button beside “Meetings and Calls”
Move the slider beside “Mute notifications during meetings and calls” to the right to mute notifications for all meetings and calls
Click on the X in the upper right to close the Settings panel
\uD83D\uDCD8 Suppress Teams notifications for the current meeting only
Once you have started or joined a meeting,
Click on the More icon (… or three dots) beside the camera icon
Click on Settings
Click on the “Mute notifications” option
Note: if you have notifications turned off by default or if you have already muted notifications in this meeting, you will see the option to “Allow notifications” instead of “Mute notifications”