My favorite thing they broke is that there is no longer an animation when launching and dismissing Spotlight in its Launchpad mode (i.e 4 finger pinch on trackpad). I mean there is an animation, but it's only visible if I'm pinching slowly. If I do it at normal speed, there's just a half-second delay and then it pops in or out.

I suspect they made the animation so heavy that it reaches its deadline before it even starts, so it gets skipped.

Not sure if it's better or worse than Tahoe, where the animation (mostly) worked but app icons either popped in all at once a bit later or were rendered one by one from top-left to bottom-right.

It's such a buggy mess. When using my Mac these days I miss the polish of my Linux desktop.