Minecraft 19w13a, Minecraft 1.14 Pre-Release 3, Minecraft 1.14, 1.15 Pre-release 6, 20w09a, 1.16.4, 20w49a, 1.18.1
When you jump out of a corner, you don't move diagonally but either east or west (along the x axis).
- Position yourself in a corner
- Look exactly diagonally
- Press forward
- Press jump
→ You're jumping either into positive or negative X direction, no matter what