I'd be more surprised if they had given you a new CPU. All the Kaby Lake-X CPUs that will ever be made <em>have</em> already been made, so the supply of new ones Intel still has hanging around has likely been dwindling; Kaby Lake-X CPUs were retired in 2018, nearly a year before the consumer Kaby Lake CPUs left production.
Kaby Lake-X CPUs were never popular, so it's not surprising to end up with a refurbished one. GPU makers will quite often send you a more recent GPU, but that's easier to do since going from, say, a GTX 1070 to an RTX 2060 doesn't require a new motherboard, which you can't say for CPUs.