[tquai]

Any ETA for allowing to block Referer header from being included in cross-origin requests?

This feature has been supported in Firefox for a long time, but you have to set it in about:config via the "network.http.sendRefererHeader" integer.

  2 = always send
  1 = send only to same FQDN (what you seem to want)
  0 = never send

IMO this is one of the best bang-for-your-buck privacy configurations. I would love it if Mozilla changed the default from 2 to 1, and at the least, it SHOULD be an option under the Preferences -> Privacy tab.