No official post mortem yet anywhere AFAIK. And most of the Zen5 speculation posters have moved on the Zen 6 speculation threads.
However, one thing speculation I saw was that Zen 5 is unbalanced. For instance this
post over AT:
It's kind of crazy to think that if you're right, the Z5 core is actually over heavy and it's the Z2 era uncore that is mostly/completely holding it back anymore.
So we can guess what the priority will be for Zen 6.
Sort of goes back to:
That won’t help. Fabric bandwidth is the limitation and amd did nothing there.
Okay, there is probably more than just the fabric at play but current speculation (and more some of the more technical reviews have shown some of this) is that Zen 5 is starved.
So while Zen 5 isn't a bad part - just overhyped and overpriced at launch as per AMD's norm* - it is very little for 22 months!
(* But Zen 1, Zen 2, Zen 3, and Zen 4 did actually outperform their predecessors often by a very large margin.)
Surely AMD would have known this years ago, so why not update the rest of the CPU at the same time?
AMD's R&D budget is no longer tiny:
In 2023, AMD spent more than 5.8 billion U.S.
www.statista.com
Okay, lag times for Zen 5 might mean that we can only really consider the 2022 figures but still.
Wonder how any of this affects server?
AMD are now big enough that they really should do dedicated desktop parts. Which some Zen 6 rumours imply - if their mainstream APUs have be penny pinched to have too little cache, then maybe all desktop parts above Ryzen 3 should come with 3D cache? That would also mean that they have to come up with another idea for the IO of their APUs though - yes less PCIe lanes save power but won't sell on desktop.