The latest in a long line of simplifications and/or removals of features in Android towards a more dumbed-down, locked-down, and bland mobile operating system, Google has just begun telling developers to upload specifically rounded square icons for their apps in Google Play, the Android marketplace (though not for Android Auto, Android TV nor Wear OS).
The option was first announced last month as the first step for a rounded square icon requirement moving forward on Android and Chrome OS will become the default in two months on June 24th as a pursuit to “bring consistency and a cleaner look to Google Play”.
Currently developers have two options in the Google Play Developer Console: to let Google scale down their uploaded icon and shove it inside an ugly white rounded square on June 24th, or to tell the company that the logo is ready in which case the corners will visually be cut off and given a soft drop shadow as they are treated as rounded-circle-ready. The former will cease being an option in a week.

As so slightly hinted at earlier, I see this as yet another opportunity Google has finally taken at iOS-ising their mobile operating system for no real reason but because they suddenly decided they'd like to. It's rather annoying to see Google continuing to copy their rival when they already maintain the superior product in my eyes, but I'm sure there are some who love rounded squares to death.
Fortunately, whilst this change will make the Google Play storefront much more boring after the 24th of June, Android will of course maintain its glorious custom icon ecosystem so outside of said storefront users can use whichever icons they prefer (I'm a Rondo fan myself).
Developers can find icon design guidelines here.
Source and image: 9TO5Google