After re-testing, let's summarise: there is no RT on Series S but there was a shadow glitch. There is a performance dip on PS5 in RT mode, but this appears to be a bug as a checkpoint restart can improve matters (but not always!). Here's a vid showing that: pic.twitter.com/ilyOqhNAtC
— Digital Foundry (@digitalfoundry) November 24, 2020