Appliance for Raspberry Pi 4: Reset system to factory conditions leads to a damaged sources.list file

after applying "Reset system to factory conditions " in Settings>>System I found to my surprise /etc/apt/sources.list damaged in this way:
deb buster main non-free
deb buster-backports main
deb buster/updates main contrib non-free

After removing the ip numbers and ports in every line manually “apt-get update” worked again without error.