I have heard that most if not all of CX's outbound flights from HKG have been subcontracted out to HongKong Beijing Air Catering Ltd or of similar mainland ilk for meal preparation. As part of yet another cost-cutting measure that was undertaken by senior management.
Meanwhile, the meals actually prepared by CX Catering are in fact at a higher standard of quality because those are the ones supplied to the other airlines flying out of HKG. This would also explain the discrepancy between CX and KA as they are not the same company.