https://wccftech.com/amd-ryzen-7-5800g-cezanne-apu-spotted-features-8-zen-3-cores/

So far, we have only seen the AMD Ryzen 7 5700G Cezanne 8 Core Desktop APU in action but it looks like team red has an even faster APU in the works, the Ryzen 7 5800G. Spotted within the TechPowerUp GPU validation webpage, the APU could be the flagship model for the Ryzen 5000 Desktop APU family.

Since the APU was spotted within the GPU-z validation webpage, we don't get to see any detailed specifications such as clocks, cache, TDP, etc however, the page does list down the GPU specs & just based on that, we can tell that the chip being tested is an early engineering sample. So as for the CPU specifications, Cezanne Desktop APUs will cap at 8 cores and 16 threads. You will get 16 MB of L3 cache and slightly higher clock speeds than Renoir Ryzen 4000G Desktop APUs.