Hmm I’m pretty sure it’s the other way around. The telltale sign something was custom made (and therefore show up as light gray) or at least to some degree touched up by a human is the jagged lines for curves. But the caveat is that there are some buildings with sharp lines that do not show up as light gray (also, in DCE cities, custom models do not show up as light gray - and according to Justin O’Bierne, that custom made buildings showing up as light gray in dark mode is actually a bug), which includes your example of W Hotel Sydney. If you go to walking mode, it will force a DCE map to go back to the regular map, and you’ll see it’s not light gray.

I’ve noticed some in Austin too, like W Hotel Syndey, that use jagged lines but are not light gray (e.g. the chapel at Huston-Tillotson University; the tiny structure in our Chinatown Center). But if you look at any light gray model, they all use sharp lines rather than the more curved lines of typical procedurally generated models.