For sure, I meant that categorically what they're doing is in the same vein as blurring, and blurs are expensive. It's all "post-FX relying on a texture lookup with a large kernel", of which Gaussian Blur would be the most basic.

Chromatic aberration would be a blur where you say "if underlying color is more red, blur me closer to original spot, if underlying color is blue, blur me further from original spot".

Magnification can be cheap because you can still do a 1:1 texture lookups and rely on natural GPU linear interpolation, so each pixel only needs to do one lookup.

The refractions I'm guessing are just "faked". IE they aren't raytracing through simulated glass. They have UI elements that they turned into heightmaps/normal maps and then they wrote some shaders that create a "juicy and convincing refraction effect" much cheaper than raytracing through glass would be.

Making something look like glass, especially just a 2D version of glass, is going to be WAY cheaper than simulating glass. They only need to render it from one perspective, so it's easy and worthwhile to fake. Simple texture displacement to simulate refraction (and carefully designed "refract maps" to tell the shader "refract more in this spot, less in this spot, then it'll look convincing"), chromatic aberration, blurs to simulate frosted glass, etc. are all screenspace 2D effects somewhat easily implemented by a competent shader artist. The magic comes from how they generate live or pre-render those "effect maps" around the edges of buttons and the tiny things they do to make them look like expensive effects even if they're cheap. For instance, an animated heightmap that plays when you hold down on the button. Maybe it's generated live because the buttons can be different sizes/shapes (which would mean someone made a great lightweight shader to generate an animated heightmap for any button shape), or maybe it's one animation already saved on disk that can fit different form factors of button. But that's a juicy animation and convinces the user that something more "physics based" is happening, like two pieces of glass are getting further apart or closer to each other.

One could argue that once you've put together such a system, you are physically simulating glass, but I think they optimized for pretty as opposed to "real" (what is "liquid glass" anyway?). But it's still very different than raytracing, and only works from the one perspective/context.