Frédéric

I was unable to test it because of MC-92255

The console outputs nothing concerning the problem. It's only a bad GUI redirection.

[10:24:47 INFO]: Client> [10:24:47] [Server thread/INFO]: Fredb555 lost connection: TextComponent{text='Illegal position', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}

I'm being kicked from solo, the screen with the message "Connection Lost" pops up with reason "Illegal Position". When I press "Back to title screen", it brings me to the Multiplayer server selection menu.

To reproduce it quickly, go in a Singleplayer world (a new one preferably), and do the command /tp ~30000000 ~ ~ two times. You will be kicked and you will understand the problem when clicking the button.

When you go in F3 the crosshair changes to that thing, have you pressed F3? I do not have this problem