At this point I am pretty sure it's the loud vocal minority that hates it. Vast majority is either indifferent or actually likes it (but liking something doesn't sell).
I've seen far more non-design-obsessed people (normals) complaining about it, but in the end i think the better question is why? What possible purpose does this serve other than key-jangling? It is a distraction for most people and a waste of screen space and probably gpu cycles, why are we shading and filtering on every frame on every window and modal? Just render the pane and put the fries in the bag.
The waste of screen space is the big one for me. It feels like every company is racing to dumb down their products and fill their UI with whitespace instead of using that space for controls or content. My bank just redesigned their website and now even checking the balance of a few accounts + credit cards requires scrolling on a 1080p display. Ridiculous.
I think the vast majority's friction points with liquid glass come from the other changes, like the redesign of Messages and the calling functionality.