It depends. What makes RDNA2 RDNA2?If it's "rdna1" but with features of rdna2 and on rdna2 tech process - it is rdna2
But I partly agree. PS4 Pro GPU had some feats from Vega (for example double speed with half precision (8bit I think, but Im not sure)), it wasnt only doubled PS4 GPU as many said.
Same is here. Sony built on top of RDNA1 own custom GPU. It sure can be on level of RDNA2 or maybe higher.
It can have some feats from RDNA1 , some from RDNA2 and some which are not used elsewhere.
But point was, if they built on RDNA1, maybe they accepted, that max.limit of CU is 40 and that could be a reason, they needed to boost clocks.
It makes sense - logically. But I dont say its truth. I really dont know. It depends how long Sony cooperated with AMD vs MS and AMD.