A WCCFTech investigation into AIB Z590 partner boards indicates that Intel's new platform will only support the PCIe 4.0 standard with Rocket Lake S processors. While Comet Lake S owners will be able to use Z590 boards, they'll be missing out on this key feature that Ryzen 3000 and Ryzen 5000 parts already support.
https://www.notebookcheck.net/Comet-Lake-S-won-t-be-getting-PCIe-4-0-support-on-upcoming-Intel-Z590-motherboards.512967.0.html
Wasn't it already announced with the previous generation that it won't be getting pcie 4 no matter the platform? It was also reported here if I'm not mistaken..