I can confirm this is also an issue for me. blue background on a HP 3055A using Ghostscript 9.26 on Ubuntu 18.04. I have regressed to 9.22 by running
sudo apt install ghostscript=9.22~dfsg+1-0ubuntu1 libgs9=9.22~dfsg+1-0ubuntu1 libgs9-common=9.22~dfsg+1-0ubuntu1
and the blue background issue has been resolved.
I can confirm this is also an issue for me. blue background on a HP 3055A using Ghostscript 9.26 on Ubuntu 18.04. I have regressed to 9.22 by running
sudo apt install ghostscript= 9.22~dfsg+ 1-0ubuntu1 libgs9= 9.22~dfsg+ 1-0ubuntu1 libgs9- common= 9.22~dfsg+ 1-0ubuntu1
and the blue background issue has been resolved.