Safari 17.1 iframes referrer policy in Private browsing mode too restrictive

Hi,

I'm seeing an issue in Safari 17.1 and above in private browsing mode where an iframe's document.referrer property is empty. I've added a referrerPolicy attribute to my iframe but Safari ignores its value. Disabling the Use advanced tracking and fingerprinting protection option lifts that restriction and results in the document.referrer property having a value as normally expected.

What change introduced in Safari 17.1 for private browsing mode could be the cause of this behaviour? Is it now enforcing a no-referrer referrer policy on iframes? This article seems to hint that the referrer policy would now be origin, not no-referrer, but I cannot find any confirmation of this on Apple's website, and this should anyway not cause the behaviour I'm seeing.

Is this a bug or a known issue?

Is there any way in HTML/JavaScript to circumvent this behaviour?

Cheers,

Oliver