The first indications of an RDNA3-based Navi 31 GPU have surfaced in the macOS 11 Big Sur Developer Beta 1 driver code. The driver also contains references to upcoming AMD APUs such as Van Gogh and Cezanne along with HPC accelerators such as the MI100 and M200. With the MI200, AMD could be looking at a multi-chip module (MCM) approach and that could trickle down to Navi 31 as well.

https://www.notebookcheck.net/First-references-to-RDNA3-Navi-31-Van-Gogh-and-Cezanne-spotted-in-macOS-Big-Sur-AMD-could-join-Intel-and-NVIDIA-in-opting-for-an-MCM-design-for-upcoming-GPUs.478032.0.html