Signed Exchanges (SXG) is a subset of the emerging family of specifications called Web Packaging, which enables publishers to safely make their content portable, while still keeping the publisher’s integrity and attribution. In 2019, Google Search started linking to signed AMP pages served from Google’s cache when available. This feature allows the content to be prefetched without loss of privacy, while attributing the content to the right origin.
Today we are happy to announce that sites implementing SXG for their AMP pages will be able to understand if there are any issues preventing Google from serving the SXG version of their page using the Google AMP Cache.
Check Out Original Post https://webmasters.googleblog.com/2020/08/identify-and-fix-amp-signed-exchange.html