small white window that opens during sharing in a meeting

Hi,

I've Teams vers. 26120.3106.4722.3411.

For some time when I access to a meeting and sharing the screen, a window or a presentation,

a small white windows appears at the bottom right and I cannot close it.

To close this window and to prevent it from opening again I need to disconnect to Teams also for 2-3 times.

Well, how could I solve a such issue permanently? Thanks

This is the window image that I can capture: