That said, according to that StackOverflow page, the error only appears in DevTools. That's not as bad as it sounded at first. I was worried it would be an IE-style alert on page load, for example, or a visible bar across the top of the page. It's not, it's just spam in the DevTools console.
That's correct. I posted that answer on StackOverflow, and as far as I can tell from testing so far, it is just a warning in the DevTools console as noted on the StackOverflow answer, and there shouldn't be any other negative impact :)
Isn't this the sort of thing .well-known is for? Presumably Google are doing it this way because less people can create headers than can make a text file.
`permissions-policy: interest-cohort=()`
It's only deployed on a test set of Chrome browsers so far, and it does create a warning message on browsers that don't support it. [1]
[1] https://stackoverflow.com/questions/66997942/error-with-perm...
Edit to note support for blocking this!