The bug
When the player is in a space that is just one block tall, it can walk and sprint at normal speed, which seems illogical since that is not possible if the player is sneaking in a 1.5 blocks tall space (MC-147270)
To reproduce
Put a trapdoor at a wall and open it
Go inside of the trapdoor
Close the trapdoor while you're standing in it
You're now "crawling"
Dig a tunnel
Walk into that tunnel, and try to sprint
❌ You move at normal walking / sprinting speed
violine1101
Is this the same as "dive-mining" (put water above the 1x1 tunnel, run into it with Ctrl and you'll sneak into that 1x1 hole, then grab back the water and continue mining)? Looks like it is. I hope it never gets fixed 🙂