worldvision.de: Rules with $third-party modifier don't work

[Sergey-Lyapin]

Rules with $third-party modifier don't work on this page:
https://www.worldvision.de/informieren
For example:

Screenshots

[sxgunchenko]

It seems like CoreLibs cannot detect that these requests are third-party since they have no referrer. By the way, you can see it in the screenshot too: the sources are empty.

[ngorskikh]

We could use fetch metadata for $third-party detection: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-Fetch-Site
Would only work in Chrome, though

[sxgunchenko]

We could use fetch metadata for $third-party detection

yup, that seems like it could work

Would only work in Chrome, though

actually, FF behaves pretty similarly to Chrome