Wrong the CPU cores are the same, the CPU isn’t being pushed its limit at all. It’s limited by PS5s overall power consumption limits.
Here is the topical on form information, for those interested - where Cerny himself states they increase the frequency/speed of the CPU. Frequency means Speed. So they do in fact Increase (not decrease) the standard CPU speed and both CPU and GPU run in BOOST mode.
They then decrease the CPU speed as needed to alleviate heating/strain on the CPU and to increase performance decrease performance of the gpu.
But make no mistake, the CPU as standard on Ps5 is burdened by a higher speed than it was intended.
Translation - we continuously overburden the CPU and GPU by overclocking both and attempt to alleviate that burden by using variable frequencies in order to relieve strain on either the CPU or GPU.
Overclocking as a solution to catch up performance wise is not a preferred solution, it stresses the CPU and GPU and may eventually limit it's lifespan.
Again, Cerny Literally Verbatim states - "WE increase the frequency of CPU and GPU, until they reach the capabilities of the system's cooling solution"