“Goblin Mode” is a slang term which means in essence to act in a selfishly indulgent manner, generally with out regard or contrary to social norms and expectations. The exact meaning can be a bit amorphous at present, but that’s the gist and it may also imply greed, slovenliness, sloth or laziness, and can be described as a way of being or a philosophy which is counter to “self improvement”- to embrace ones nature and urges.
:)