The bug is as followed,

When you startup Minecraft Java edition 1.13 with the game launcher it wil get stuck whenever you reach the main screen or even the mojang screen.

After some trial and error i found that Discord is the causer.

After i started up Minecraft without Discord on it works just fine but when you try to startup Discord then Discord wil crash. The same thing happens when you do the opposite but then Minecraft gets stuck.