And the flashes are as if someone is taking pictures of what I look at.
I think the best thing at this point - if you can accomondate whatever is disclosed - is capturing and showing a screen capture of what you experience.
On what version and device are you exactly as in full version string? I don’t know when they introduced it, but through Settings → Security & Privacy → Privacy Dashboard you can see when what permission was last used by what app. Enable “show system” in the upper right too.
If you can do logcats you’d be better able to tell what’s going on. A screenshot action is logged very detailed, by what instance, what app etc, examples:
D Screenshot: Screenshot request: ScreenshotData(type=1, source=0, userHandle=UserHandle{0}, topComponent=ComponentInfo{com.android.permissioncontroller/com.android.permissioncontroller.permission.ui.ManagePermissionsActivity}, taskId=1603, originalScreenBounds=Rect(0, 0 - 1080, 2160), originalInsets=Insets{left=0, top=0, right=0, bottom=0}, bitmap=android.graphics.Bitmap@62e029f, displayId=0)
D Screenshot: Screenshot request: ScreenshotData(type=1, source=0, userHandle=UserHandle{0}, topComponent=ComponentInfo{foundation.e.mail/com.fsck.k9.activity.MessageList}, taskId=1627, originalScreenBounds=Rect(0, 0 - 1080, 2160), originalInsets=Insets{left=0, top=0, right=0, bottom=0}, bitmap=android.graphics.Bitmap@bf5b521, displayId=0)
If you feel paranoid, a factory reset is the way to go. But it’s hard to tell from outside what is going on.