As far as I understand, this only affects sub requests (iframes, Ajax requests, scripts, CSS, etc), and not the main request. In a redirect, the third party si

As far as I understand, this only affects sub requests (iframes, Ajax requests, scripts, CSS, etc), and not the main request. In a redirect, the third party site is used as a friest party request, and should not be limited by this. See same site cookies and referrer policy to limit how much information is leaked to a third party with redirects.