Basically, a young man who goes by the name Elite Gymnastics said some things on a blog post about Sky and Charli XCX not really being the future of "DIY" pop given that they're both signed to a major label and work with producers. He also said Charli's music was "a mangled, grotesque approximation" of Grimes', which is a bit harsh.
Charli XCX then responded to it all here in quite a well-argued post which boils down to 'oh fuck off'.
Sky then responded on Facebook, adding: "Collaborating with people is MY choice! Throwing bags of money at people didn't get me to where I am & I didn't record songs BY people. I made songs WITH people. There is a difference."
So there you go.