I'm also shocked to hear that designers at Microsoft are designing features for Windows on a Mac. I presume these are 'UX Designers' or 'Interaction Designers'.

Imagine the opposite scenario for Apple and how absurd it sounds: designers at Apple designing features for MacOS or iOS using Windows OS laptops.

This prompts the following question: What design apps are the Microsoft designers using on a Mac that they can't use on a Windows machine? (Is it Mac-only Sketch?)