It’s about the Intel Denoiser not working with Blackwell series GPUs (the 50 series) - the fix was released along with RC1 for Corona, “Added support of Intel Denoiser for Blackwell (NVIDIA 50-series) GPUs.” in https://forum.corona-renderer.com/ Chaos Corona 13 for 3ds Max - Daily Builds Changelog #msg232607
(We had to wait for Intel to make OIDN compatible with Blackwell 
)