This is true for any X3D / V-Cache CPU. Hence why I'm ok running 4800 MT/s ECC UDIMMs (the only officially supported MT/s value) (enabled in BIOS) (ASUS is the only company officially supporting ECC in consumer AM5) (bought in 2023, I think).
While DDR5-6000 is regarded as the sweet spot for optimal gaming performance with X3D processors, AMD says that the Ryzen 7 9850X3D can perform similarly with cheaper DDR5-4800 RAM. The difference is said to be around 1%.