Here's my personal canary in the coal mine that something must be fundamentally broken in Apple's software development process: - on a recent macOS version, right click on the desktop, select 'change wallpaper' => the new settings panel opens - click on 'Custom Color' - now hold and drag around the 'color cursor' in the color selection circle for a few seconds - stop dragging and notice how the color cursor continues…
EDIT: can repro. But it's very important to note: you need to have a color selected already. So select a color with the + sign, close the app, open it, top right click custom color, and then the bug appears, although not like you describe: the color selection is easy, it jumps around for 20ms during dragging. If this is what we call "low quality" I'm happy to stay on Mac.
Might be a reason why it wasn't fixed if you didn't include that vital step in your repro.