Firefox not respecting custom headers set

I have the following headers set

  Cache-Control: public, max-age=604800

  Cache-Control: public, max-age=604800

When visiting my site in Chrome & Safari the appropriate headers are used in the response for the assets under these directories.

However, in Firefox (72, macOS), they are not respected and instead for some reason Netlify servers are returning cache-control public, max-age=0, must-revalidate for these assets.

The request headers being sent are

User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:72.0) Gecko/20100101 Firefox/72.0
Accept: text/css,*/*;q=0.1
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
If-None-Match: "84a2631a5a1a24f6b03bf9fb2b5b2f7a-ssl-df"
TE: Trailers

hi there, thanks for letting us know about this.

Could you provide us with the x-nf-request-id for this, please? then we can pinpoint.