If this is the click target area specified by the designer (or it was simply unspecified) then it's absolutely the designer's fault. I'm a UX designer and I've made mistakes like this before, though this one is pretty egregious because the issue is core to the interaction.

It's sometimes easy as a UX designer to forget to specify some of the smaller details (though this example isn't what I'd call a "small detail"), particularly because they're the kinds of things you don't notice when they work, and I don't have to implement it. The developer has to sit down and write code for what will or will not happen.

I've made mistakes in the past where in an mobile interface I neglected to specify the click target area for some controls. Typically the minimum clickable area we'd use was something like 44x44 but the visual was smaller than that, and I didn't specify it, so the developer made the visible element the one that would respond to the click events. It was too small and it caused issues. I owned up to that one, I didn't want to let the developer take the blame for that.

I've also been fortunate enough to work with developers who would notice these things and then ask me if it was intended and whether they should increase the clickable area. I was always so grateful to have colleagues like that, and I'd always offer to set some time aside to come take a look at things on their local environment before they moved things forward just to catch any issues where they could immediately fix it instead of having to push fixes later on.

I don't know where the failure happened at Apple, but based on what I've seen from "Liquid Glass" it's clear there's some real institutional failures involving either the design leadership, the development leadership, or somewhere in between both. It's really quite embarrassing the quality of GUI and UX that has come out of Apple recently.

This is the first time ever where the hurdle of rolling back my iPhone to an earlier version of iOS feels worth the effort. I disabled as much of the liquid glass effects as I could because I found it difficult to read and now it all looks like shit, whereas before I could read it and it looked nice.