No background image

Hello to all, I have a problem with background image.
The image is correctly inserted and optimized as explained in the faq, but in the site the background image is not there.
until today everything was fine, after I put the meta of google and bing in Site Header, the image disappeared.
I tried to remove the meta, but the background does not appear.
some suggestion?

browser firefox
Linux Mint 20.2 Cinnamon
ghost online