The bug
Disconnecting from a server (integrated Singeplayer server as well) prints that the player was banned:
Marcono1234 lost connection: TranslatableComponent{key='multiplayer.disconnect.banned', args=[], siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}Note: The fact that it prints the text component instead of the value is MC-59535.
@@unknown please choose a meaningful summary next time.