You should make the request for a downgrade product key kit via your reseller. for example (Dell / HP)
https://www.dell.com/support/kbdoc/en-in/000120661/dell-emc-microsoft-windows-server-2019-oem-and-windows-server-2016-oem-downgrade-kits-availability-at-the-time-of-server-purchase
https://community.hpe.com/t5/alliances/curious-about-windows-server-2022-downgrade-rights-get-all-the/ba-p/7165240#.Y7bUa1HMJPY
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