Minecraft starts to go weird behind the Worldborder.

What I expected to happen was...:
That the command tells me: "You can't teleport more away" (like in 1.8)

What actually happened was...

• NO Commands are working. Not even normal Chat Messages
• Minecraft is starting to have Lag Spikes
• New Chunks are starting to render weirdly (Ex: Only Top of Trees are getting rendered, I can see the Lava o other chunks but no other blocks in the Underground)
• If I try to close Minecraft I get a dark grey screen that still has FPS (shown by my FPS Programm) but has nothing on it (I can only close it with my TaskManager)

Steps to Reproduce:
1. I tried teleporting to /teleport @p 30000000 100 0 (I got teleported behind the Worldborder and couldn't move any further behind it)
2. I tried /teleport @p 31000000 100 0
3. I got teleported to 30000000 100 0 and BOOM the Bug has started

I added some screens that I took

PS: I noticed that Blockupdates also wouldn't work anymore.

Everything tested in Singleplayer with Gamemode.