Seems XSS prevention was implemented in a weird way, hence why the text following a > doesn't get cutoff. "< abc def > xyz" renders only "xyz".
Weridly enough, typing < renders a "<" just fine in the bottom chat, but not the top 'dialog box' chat.
Actually attempting to render HTML elements by typing <iframe src=""></iframe> (<iframe src=""></iframe>) didn't work.
But <h1>TEST (<h1>TEST) made the top text tiny, which is 99% a spooky exploit...
It seems that Deadlock uses its own XML style chat formatting system...I wonder what tags change the text color?