I upgraded to 11.0.1 Beta (20B5012d) from Catalina and initially saw no networking issue as I had when I upgraded to a previous Big Sur beta.
However, after a day and maybe a reboot I saw the same problem and solved it with the previously shared solution:
sudo rm /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist && sudo killall -9 configd
In other news, sidecar stopped working and I had never had any issue with it previously. Of course, this is all on a spare machine used for testing betas
