Zen 5 rumors are bubbling up more frequently since a few days. A first few alleged benchmark leaks of engineering samples have leaked, too, but are IMHO unreliable. Various vendors of AM5 boards have published BIOS updates with (preliminary) support for Zen 5, apparently confirming the "Ryzen 9000" naming scheme.
A few people closer to sources have made ominous remarks about more distinct variants of CPU chiplets: 1. with 8 high speed cores, 2. with 16 dense lower power cores, and newly 3. with 16 dense cores not optimized for power, but for retaining as much max clock frequency as possible in the smaller silicon area. Number 1 would be the traditional high performance cores we already know; number 2 would be for high density servers as before, but the new variant 3 would be for workstations or desktops, where there is only ever a single socket dissipating heat.
In some circles, the hype is strong for IMHO unrealistic Zen 5 performance expectations. I can believe that an isolated benchmark exists where Zen 5 is indeed 40% faster per clock than Zen 4, but IMHO that would have to be an AVX-512 benchmark - Zen 5 is said to execute some more operations at the full 512 bits width instead of double pumping 256 bit wide ALUs. But for general spaghetti code, I don't see the IPC improvements anywhere near that.
Along similar lines, a few people closer to sources (presumably in the orbit of motherboard vendors) claimed that qualification samples are already available to finalize firmware and software support. But none of those chips have leaked any benchmark data yet.
In any case, the activity behind the scenes has picked up pace. Seems that Zen 5 is on track for a timely release. I would advise to not believe the hype (unless you care for AVX-512 performance). There will be improvements, but unless AMD decides to give us more than 16 cores on AM5, the jump won't be huge.