Please perform the below mentioned steps to resolve the issue:
> Stop the background running app (Tap on the left soft key and close all the running apps).
> Ensure 20% of internal memory of device is free (Scroll down notification panel > Setting > Device care> storage).
> If device hangs in any particular application/game then clear cache memory of that application (Settings>apps> tap on that app>storage>clear cache)
For further assistance, register your concern in Samsung members app (Open Samsung members app>click on “+“icon>send feedback>Error report/ Ask Questions).
Further, we have noted down the feedback regarding always on display feature in Samsung device.
Providing a continued great experience is our first priority. We would take this feedback for further improvements in our upcoming launches.
Team Samsung Members