It is constant, daily and at random times. I haven't changed screen saver from the original one. I can still provide you more info depending on your questions.
The auto restart feature that @SamsungJoJo mentioned is where I was headed on that. You can schedule a restart, but if yours is a random event, that probably knocks that out. But to make sure, check Settings > Device Care > 3 dots upper right corner > Advanced > Auto Restart > and either make sure this is turned off or open it and changed/reset times and dates. @