If you believe the die size to be true, then no matter how high they push the clocks difference is going to be at least 20% which is quite significant, it doesn't align with what Schreier wrote about specs of the two being similar.
The running narrative is that early devkits from both companies stated they wanted 10+TF.
If we are to believe tomwarren he claims that internal first party studios were the only ones privy to the 12 target.
Fast forward to December - Playstation 5 is still around 10 TF and Xbox has a controlled leak to Windows Central of a 12 TF Target.
This explains why earlier in the year Andrew Reiner and other journalists including Klee may have heard PS5 was performing slightly better.