There was a golden period of OS X roughly between 10.5 and 10.9.

Up to 10.4, windows were too textured: stripes, brushed metal.

In 10.5 till 10.9 we got to enjoy the beauty of Aqua paired with calm, tasteful gray window frames and controls that had visible depth.

From 10.10 till 10.15 was okay-ish: the flat took over, but we still had contrast and shapes.

Starting from 11, everything became rounded, low contrast and lost visual cohesiveness.

10.5 till 10.9. We didn’t know how good we had it

Look at this. Just look. How icons are all different sizes. How labels lack horizontal padding. How border around “CPU” disappears. How “Search” text is not vertically centered. Look at the ugly pinkish gray background. I refuse to believe a human designed it. No human with eyes could purposefully do this. It’s not rocket science. It’s basic design hygiene.
@nikitonsky seems to me the visual style and the bugginess are two separate questions no? you can do the calmer visuals without the specific quality and contrast issues you pointed out here - and without those that last screenshot would look nicer than the in-your-face y2k aesthetic of the first ones
@tbernard technically yes, in practice they seem to correlate. If people care, they get both right. If they don’t, they mess up both