oklch uses the oklab color space.

The oklch color space is polar: it’s a cylindrical transformation of the oklab cartesian color space.

That's quite misleading. The parent commenter was asking about gradient (interpolation between colors). Gradients look completely different in oklch and oklab.

Well yes, it's a different coorsinate system, so gradients would look different. It is still the same color space, but I agree I could have worded that better.