The bug

I moved from a glass block to a soul sand block while crouching adjacent to lava. I knew I would catch on fire because of the 7/8 hotbox, but I also fell off, even though I was crouching.

How to reproduce

1. Place down any normal height block adjacent to lava, crouch on the edge of that block
2. While crouching, move to soul sand which is also adjacent to lava