Once I noticed just how many app logos have white-on-black color schemes — including Threads, the BBC, Uber, Apple TV and, yup, The Washington Post — I had to know what the heck was going on.

The Cash App logo is being displayed on a smartphone screen and on a computer screen in Athens, Greece, on April 30, 2024. (Photo Illustration by Nikolas Kokovlis/NurPhoto via Getty Images) ...