Hello Ahmed,
Unfortunately, it is not possible to downgrade RDS CAL 2022 to 2016. RDS CALs are version-specific and cannot be downgraded to an earlier version. Additionally, RDS CAL 2022 is not compatible with Windows Server 2016. You will need to upgrade your server to a version that is compatible with RDS CAL 2022 or purchase RDS CAL 2016.
Thanks,