I've been theorizing this for sometime.
If PS5 uses Infinity Cache, it would mostly be a cut down version.
There was a tweet the other day that said Infinity Cache is more dense than Zen 2 L3 Cache.
PS5 may very well have 64MB @ 43.3mm2 or 32MB @ 21.65mm2 or even 16MB @ 10.83mm2.
Many where saying the PS5 448GB/s Bandwidth and 256-bit Memory Bus wasn't enough.
But if Mark Cerny incorporated Infinity Cache, which gives a 3.25x Effective Bandwidth.
That would give the PS5 an Effective Bandwidth of 1456GB/s, which is insane.
So maybe Infinity Cache Effective Bandwidth scales with size.
E.g.
128MB adds 1152GB/s
64MB = 576GB/s
32MB = 288GB/s
16MB = 144GB/s and so on.
So if the PS5 uses 32MB of Infinity Cache @ 21.65mm2,
448 + 288 = 776GB/s of Effective Bandwidth, which seems about right for next gen.
Also, this 32MB of Cache might be shared with the whole system (GPU+CPU+I/O), like how the 16GB of GDDR6 is shared which the CPU and GPU.
Thus, saving space.
This is just my thoughts, so don't take these configurations too seriously.