𝗘𝗫𝗣𝗟𝗔𝗜𝗡𝗔𝗧𝗜𝗢𝗡:

Strange player movement happens in water past 30m blocks by using an ender pearl.

𝗛𝗢𝗪 𝗧𝗢 𝗥𝗘𝗖𝗥𝗘𝗔𝗧𝗘:

By teleporting to the world border around 30m blocks from spawn, and going past the border with a pearl. There will be some wall that stops you at 2999999 blocks. You cant go further.  But by throwing an ender pearl past the 30m block invisible wall at an ocean, will cause a strange glitch and your legs will be in the ground. Sometimes, you will be in the floor and suffocating.