Sec-Purpose: Prefetch is sent when the document fetches a <link rel=prefetch> resource.
It allows servers to do the following:
opt-out from prefetching, e.g. by sending a 503 response with Cache-Control: no-store
Some pages that rely on requests for analytics and for information such as "last visited". This allows them to not count the prefetch as an actual visit to the site.
See https://github.com/whatwg/html/pull/8111
Sec-Purpose: Prefetchis sent when the document fetches a<link rel=prefetch>resource. It allows servers to do the following:503response withCache-Control: no-store