If name of world is "tnt" it displays as "TNT" instead.

Can confirm.

This is an interesting bug as it only appears to affect the word "tnt", and it only capitalizes it if it's the only word in the world's name. For example: if I name the world "my tnt world", it won't capitalize it for some reason.

tnt is a text string for Markeptlace, I mean tnt=TNT. That is why it was capitalized