It's a mistake.
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Actually, I believe that "that" specifically would be „jener“.
Sort of true, but a better comparison would be jene Milch = "yon milk".
Never heard of "yon"? Nor do most German speakers use jene in daily conversation. They're both more theoretical words than practical ones.
In practice, "that" is der/die/das -- which can also be "this".
dieser/diese/dieses is "this" -- it's not generally possible to translate it as "that".