In a way this shouldn’t come as a surprise. This is because Adobe has not updated either app for years. With Photoshop Mix, it was updated about 3 years ago, while Photoshop Fix was updated two years ago. These apps were designed to be the free equivalent to Photoshop, although for the most part the features were kind of limited and weren’t designed to be comprehensive editing tools.
However, if you don’t need that much from a smartphone photo editor, then perhaps these apps might still be worth checking out. You can download them now before they get removed and keep using them until they stop working.
As for the reason behind their removal, Adobe says on its FAQ page, “Your favorite features, tools, plus more, from Photoshop Fix and Photoshop Mix are being added to Photoshop Express, where we are focusing and dedicating our resources to provide you with the best all-in-one photo editing mobile app in the market.”