I actually though they would have done that, but it used the regular "iPhone Distribution: Facebook, Inc. (In-House)" cert, they didn't even create a shell entity and get a new one. Reports say Apple has revoked this cert, breaking all internal (legitimate) apps and possibly creating quite a bit of chaos for internal ops.{1} Their separate Apple Developer Program organization account, used to deploy TestFlight public and private betas and App Store apps, as well as local deployment to a small number of devices without Apple involvement for development testing, is not affected.

The intermediaries may or may not face consequences if they have separate agreements with Apple, but they did not use any Apple products to do their part and have not violated anything with Apple.

{1} https://www.theverge.com/2019/1/30/18203551/apple-facebook-b...