If guest posts without giving a nickname, nickname is  "Guest", thats fine.

But if guest gives a nickname, lets say "Bryan", in post it shows "Guest Bryan" as nuickname

Same thing old posts where account has deleted. If users nickname was "Lindy" before deletion, now its "Guest Lindy"

"Guest" group shows under avatar, whats the point adding that "Guest" in every nickname?

 

That wasnt like this in 4.0.x

Nice, i can fix this in translation.

 

Guest %s

to

 %s