Welcome to Android Central. We really will need more information to offer you the best advice.
Do you have a case on this device or any attachments attached to it?
Do you have the screen timeout and a lock time set?
Do you have
palm swipe to capture enabled? You don't say what the photos are of but this setting is for screenshots.
Do you have double tap power button to capture enabled?
When you find it taking photos, as you did the other night, what did you do to get it to stop taking the photos? Just pick up, move the device, press a button, restart? What did you have to do to get it to stop?
Is there a screen protector on the device? Is it in good condition, no bubbles, no dog eared corners or edges, clean, less than 6 to 8 months old?
When you mention the notifications, do you mean that there were notifications from apps wanting camera permissions back? What apps are giving you these notifications? It is kind of unusual for an app to request permission for something like the camera without being opened by the user. I would say typically any app needing camera permission would wait until the app is opened, then realize that it needs permission and only then would it ask. If you are getting requests from apps that you aren't using that sounds like a problem. Please share what apps are requesting permission?
Speaking of apps, do you have any apps from places other than the Play Store, Amazon App Store or Samsung's Galaxy Store? Downloading and using apps from random web sites is not the best practice. The best practice is to get apps from trusted places like those I mentioned. If you have apps from other places, you might try disabling them for a short time to see what this issue does.
Well let us know what you find and we'll do what we can to offer you better advice. To receive notifications when others reply to your thread and to leave comments of your own please take a minute to create an account. It will help you communicate and get help. This link will guide you through how to do that...
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