Screen "protector".
It fell from about 1 meter onto some hard plastic. This does not sound that bad so my current theory is that all the previous falls reduced its health to 1 HP and just lost that last one.
But still, what the fuck, Samsung... I had the cover and the screen protector (hardened P9 glass something) on it since day one.
I had another phone with a very similar injury but that time it got a rock to the 2mm gap between the case & protector.