So there I was… Just routinely completing the mission of not having to fight any more kappas. Yes, the kappas mission. Which I am also doing for the the Gashadokuro of not having any more of these… So 14-9… On wave 3 of 4… Tiles 5hat formed the dragon shield tiles seemed to explode kind of strangely. Then boss wave started, and this showed up.
Yes, a piece of the tiles gone. Almost if finger snapped away by Thanos. Game still continued and I can see tiles got blocked by the missing space (like the ice cubes during winter event).
The game went back to normal after the stage ended. But that was weird.