Curious what snapping tool you're using, because the built in Windows snap on a 34 always felt clunky to me too. Have you tried PowerToys FancyZones? It lets you set up custom zones so you can park Illustrator on one side and drag palettes into a saved slot instead of fighting the default split. Also, what resolution is yours? If it's the 1080p tall version, the vertical space might be why the split feels cramped for palettes.

Notice this same gap everywhere once you start looking. Concert photos with wild colors that the room never actually had. Phone shots of a sunset that crank the orange past what your eyes saw. Even food pics where the plate looks way better than it tasted. Cameras grab light over time and stack it up, our eyes just take what's there right now. I quit trying to make my astro shots match my memory and just shoot for what looks good, then dial it back a little so it still feels like the same night.