Big Sur Beta 5 clean reinstall stuck on macOS Update Assistant

I’m running a macOS Big Sur Beta installer from Recovery after erasing my drive, and after running a Reinstall macOS utility for over an hour, this Update Assistant appeared. The progress bar is not moving, wireless keyboard and trackpad disconnected, I can’t find any information on this utility on the web.

I’m aware of various rebooting methods, instead, I’d like to find out if anyone is familiar with the said assistant and possible reasons for its appearance on my screen.

See photo:
https://discussions.apple.com/thread/251741106
Big Sur Beta 5 clean reinstall stuck on macOS Update Assistant
 
 
Q