I am baffled that when Apple introduced the new icon format in macOS 26 they didn't add support for some sort of "pop out"/"protrusion" layer.

Even Apple's own designers are handicapped by this, suffering from this decision and being unable to produce an icon for Preview that doesn't suck.

Also fun thing, in the macOS 27 beta, they were tweaking all the icons very slightly almost every beta build — primarily outline and shadow intensity stuff. The icons became much less glossy but more flat (e.g. Finder, Games, Mail, Phone) as a result, although some, on the contrary, started using the glass shader (e.g. Maps, and just look what they did to Chess!).