We are changing the behavior of the floating call controls in Teams meetings so that they will always be visible for Android and iOS phones and tablets.
When this will happen
We will roll this out to the respective stores beginning late September and expect the rollout to be complete by the end of October.
This feature makes it easier to access key controls such as mute/unmute. Users will no longer be able to dismiss floating call controls by tapping on the screen.
Floating controls on a phone
Floating controls on a tablet
You might consider updating your end user documentation and training.