I have a Samsung galaxy J7 that just started displaying this as the lock screen. Sometimes it displays my regular lock screen, but if I let my phone sit long enough, it will display this screen. It ALWAYS pops up, not just when my phone is charging. I don't know what it is, and the other questions I've found have suggested apps could be the culprit, but I don't have any of the problematic apps. I just want this thing gone, it blocks my notifications. Thanks in advance.
UPDATE: It seems to have been caused by the game Cube Escape: The Lake. I deleted the app and so far so good.