Cursor appears when in gameplay (in full screen)

When playing in full screen in Minecraft: Java Edition, for some reason, a cursor will appear in the middle of the screen, in which it is really annoying, it can be triggered when leaving any type of UI, but more common when leaving the chat screen.

 

Reproduce:

1. Load game in fullscreen
2. Open chat box or GUI
3. Close it, and mouse should appear.