Google SXG is a new technology for delivering instant fast webpages in results, you can find info here:
https://developers.google.com/search/docs/advanced/experience/signed-exchangeHowever Avast Web Shield is blocking browsing webpkgcache.com, as a false positive for phishing/deceptive content as seen in the attached screen shot.
I hope this message reaches the appropriate team at avast.