Mac app icons have historically featured diverse shapes, but recent macOS versions enforce a uniform squircle shape to harmonize visuals across the platform, restricting arbitrarily-shaped icons to maintain consistency and system integration. This “Squircle Jail” approach, introduced after macOS Big Sur and solidified in macOS Tahoe, trades the expressive freedom of bespoke shapes for a cohesive Dock appearance that balances platform identity with app branding. The evolution reflects broader shifts toward simplified, scalable design suited to a growing and varied developer community, emphasizing the squircle as both canvas and container to effectively communicate the app’s function while fitting into Apple's ecosystem.
The Mac Blog
Exploring the Apple Ecosystem