I have not found a solution. I downloaded the file fresh and used generate assets on it as it comes direct from Apple and this still had the issue - I have filed a radar (FB8755043).

For anyone else who had this issue, it has been resolved in build 21A5294g

I have also reported this issue. I was able to use DFU mode and restore from a device running macOS 13.5. Attempting to re-install beta 4 results in the issue immediately returning. I've also attempted to install beta 3 using a USB made using the installer but when attempting to boot that drive it says "A software update is required to use this startup disk." Clicking Update and waiting several hours, the progress bar has not moved so I am struggling to get back onto Sonoma to restore my latest backup!