(lists.webkit.org)
But if Google does this properly and uses more sophisticated browser
fingerprinting techniques, Epiphany is done for. This could be an
existential threat for non-Safari WebKit browsers. Nobody is going to
be interested in using a browser that doesn't support Google websites.
Google's expressly-stated goal is to block embedded browser frameworks
and non-supported browsers from signing into Google accounts. The blog
post says: "This block affects CEF-based apps and other non-supported
browsers." It says: "We do not allow sign-in from browsers based on
frameworks like CEF or Embedded Internet Explorer." Clearly CEF is the
main target, but I guess WebKit (and likely also QtWebEngine) is at
risk too; even if we're not mentioned directly, it seems pretty clear
that WebKitGTK, WPE, PlayStation and WinCairo ports, etc. are all
likely non-grata.
Not good at all in terms of the overall health of the web.
Starting January 4 Google will block sign-ins from embedded browser frameworks