I was flying around in spectator mode and came across a gash in the world that was a couple of chunks wide. It just cut through everything from bedrock to the sky, and the weird thing is that while the stone, trees, dirt, etc. was gone a few mineshafts were not. I didn't do anything to change it, it was just there. The ocean (with still water) didn't flow into the gash, but occasional water and lava sources underground would flow out into the void. I couldn't choose 1.8.9 for affected versions so I had to put 1.15.