Minecraft Username:
DeltaXCrafter

Brief Description:
When you stop sprint-swimming in a kelp stalk under water, you get stuck.

Instructions:
1. Go underwater, and sprint-swim.
2. Swim into a kelp stalk.
3. Stop when you're inside the kelp stalk, and you're stuck.

How many times did you recreate this?:
More than 5 times.

Result:
You are stuck, can not move, cannot swim up or down, and can't look around without it fixing the cursor back to its original position. You may also be kicked from the server after some time, as I was kicked twice when testing it.

Expected Result:
You should be able to move freely through the kelp without an issue if you stop sprint-swimming in it.

Evidence:

 

My memory isn't serving me, but it didn't look like an anti-cheat message. At first I had guessed it kicked me for flying, as I don't have fly, but it didn't mention anything like that. It just disconnected me without a very specific reason, I believe.

 

I tried to replicate the glitch only a couple seconds before typing this, on both a personal file and the server, and I could not replicate it again. It seems to have fixed itself..?