Juli Clover, MacRumors:

Facebook and Apple are squabbling over document requests in the ongoing Epic v. Apple legal battle, according to a new discovery letter filed with the court today. Facebook is involved because Facebook executive Vivek Sharma is set to testify on behalf of Epic.

And:

According to Apple, Facebook has been continually ignoring requests for documents and using delaying tactics. Apple says it served multiple subpoenas to Facebook starting in December and met with Facebook several times to narrow the scope of the requests, but Facebook has refused to produce many of the documents in question.

Fascinating chess match here, with Apple and Facebook coming to an agreement that came unraveled when Epic added Sharma to its witness list.