WPT coverage of the tests of cors at the revision 5602b0f210e3. The tests link to their results in the browsers on wpt.fyi. The tentative tests (experimental features) and the reftests are listed separately from the stable tests.
the client hint request headers (device-memory, dpr, width, viewport-width...) are not CORS-safelisted request-headers (the Fetch Standard does not list them; only Chrome does), so the request has a preflight, which cors-makeheader.py does not allow
the client hint request headers (save-data, device-memory, dpr, width, viewport-width) are not CORS-safelisted request-headers (the Fetch Standard does not list them; only Chrome does), so the requests have a preflight, which preflight.py does not allow