Problem with phone sound on Galaxy s10e

I have the doorbell installed with the app. When I open the app to view the video doorbell, all phone sounds stop .
Ringtone, media, system sounds do not work anymore.
I have to restart my phone, Samsung s10e, in order to reset sounds and make it work again.

Any idea what’s wrong here?

Regards Paul

When this happens, and you kill the app, does everything return to normal again?