It's been a "bug" for several decades now. Not everything was of shitty jagged quality in either 90s or 00s. Particularly when using some more capable image editors.
Otherwise you might as well use photoshop.
(But no I’m not kidding myself, I realize the days of using Paint to actually Paint are over)
> It seems like they could have left it as a pure “paint” app and added the fancy stuff to some new image editor or something.
Apple Text Edit vs Pages.