Eh, I think it’s a bit of both? The first books just generally where fairly whimsy and light-hearted and you don’t really need your demographics and societal structures to make sense when you are writing a whimsical, light-hearted story for kids.

The later books become darker and more serious so the artifacts of those earlier worldbuilding decisions become more and more obvious over time.

JKR is allowed to learn and grow! She just refuses to and her takes keep getting worse.

They tried expanding the world, it sucked and nobody liked it (also, the worldbuilding is so weak that it falls apart if you consider wider society outside of Hogwarts for five minutes, because the series started as books for grade schoolers)

She was already a TERF way before Covid.