This bug is a bug that makes the player get pushed off a path/soul sand block (could be other types of blocks with same issue) if there is depth near the block , if the soul sand block for exemple does not have an air block on his sides the bug wont happen . It like pushes towards the nearest "void" . And it also pushes you if for exemple there is a path block you try to jump on like a stair , the path block will push you backwards . For info this is something very deadly in the nether because you can end up in a "black hole" of soul sand where it just pushes you in lava or in a pit