https://wccftech.com/amd-ryzen-7000-cpus-am5-platform-will-only-support-ddr5-memory-comes-with-expo-memory-profile-technology/

AMD's Ryzen 7000 CPUs and the respective AM5 platform are now expected to feature support for only DDR5 memory.

There have been many hints by AMD in the past suggesting that the AM5 platform and the Ryzen 7000 CPUs will be based around the DDR5 memory standard. More recently, during the Meet The Experts webinar, AMD's representatives confirmed that Raphael, codename for Ryzen 7000 CPUs based on Zen 4 core architecture, will be their first DDR5 gaming platform. As such, users running DDR4 memory will have to say goodbye when moving to the new platform.