Nikolian

One thing that can cause this is, when you go in an end gateway, sometimes loading the chunks , you’re character loads first, falls then the chunks load after. It’s usually a good habit to press ESC and pause the game directly after travelling dimensions for the first time and allow everything to properly load.

Not saying this is why, but it’s one reason it could.

Can confirm, downgrading a Minecraft world can have detrimental effects on it. Generally try to avoid doing this if you can!

Hi RUSapache, are you by chance double tapping “Forward” on they keyboard. This will also activate sprint!

It’s activated by either CTRL or double tapping forward. Please confirm under what cases it happens.