Receiving ERR-665275 when app is idle

After downloading my app to an Android phone, all is working fine except one thing. When I leave the app open, idle, after a certain amount of time (around 1 min generally), I receive an App Unavailable message with error ERR-665275 at the bottom. Any idea what it can be?

I found another post with similar issue. I am still within the 72h publishing window?

Hi @didier.coymanohatdl, if you selected a testing download, that download will expire after 72 hours and you will see the screen with an error and stating that your app is unavailable.

Please see our publishing docs for more information.