MS has also been careful on this front. also using the wording .. based on their RDNA2 technology.
There is some evidence that I think would suggest that's not entirely clear cut what both did. But VRS is where I'm focusing my attention. There's frankly just no reason for Sony to remove it from their chip, and currently no reason for MS to have inserted their own VRS solution. Multiplatform titles that leverage VRS will have tells of what it looks like, and XSX will have it should have the same tells, if we don't see the said tells on PS5, then we know it's not present (either ever, or because the SDK doesn't yet support it).
If we see that it's not present on PS5, and we know MS inserted their own solution, that's pretty telling that perhaps the AMD Tier 2 VRS was not available for either. Which leads into the discussion if they really are using RDNA 2 as a base and customizing that... or that they started with RDNA 1 as a base and moved it towards RDNA 2.
Having said that, there are some outside reasons that could explain why MS went with their own VRS solution. I can't speak on that, but I suspect if it does come into play, we'd know at a later date. Perhaps as early as July, but I"m not expecting anything from it until 2021/22.
We won't know for a while however, there's no possible way to decode this pre-launch.