That seems like a bug right? The drawing code might be highly optimized for equal height rows but resizing cells is quite common, I’m surprised they just punt on it.
IIRC redraw doesn't happen until the sort finishes, but I use Excel as little as I can get away with, so I don't have a recent memory to rely on. That said, at a guess, reordering rows of equal height (and otherwise with no non-default properties) is probably mostly just rearranging pointers - why bother keeping row index associations intact, when the only trait of any row is the values in its cells? - while reordering rows of varying height might involve a lot of copying, or otherwise significantly more complex shenanigans, to make sure data and row properties stay properly associated.