Maybe it looks better on a nicer monitor or something. To me there's nothing terribly broken about the Tahoe UI, but it's clearly rushed because there are a ton of weird little things that just look off.

The dock is suppose to look like the icons float in a class panel, but the reflections in the glass look pixilated and the effect isn't there. The dock icons are centred in the dock, but the activity indicator on the "glass" pane make it look like they're not.

In the control panel, and other windows with a left panel, it's clear that the window curve and the panel curve aren't the same and the transparency of the panel makes it even more clear. I don't understand why some panels can be transparent, but other parts of the window isn't. There's no reason for the transparency.

The Tahoe looks like Gnome theme from 2005, it's interesting, sort of pretty, but the details makes it clear that the authors doesn't quite have the skills to perfect it.

Apple have been slacking in the UI quality control department in the past few years. I have similar issues on my iPhone SE, Apple (and app authors) clearly doesn't test on this phone, because UI elements frequently overlap.

Also I'm still annoyed about the control panel being ported over from iOS. You can't find anything and the window can't even be made wider.