Disable HTTP referrer in tor-browser caused risk?

Question

In the URL bar of tor-browser, go to about:config.

In the page of about:config, find Network.http.sendRefererHeader then change the value to 1.

Any risk?

Answer 1

This image shows what Network.http.sendRefererHeader does:

The Tor browser has set Network.http.sendRefererHeader to 2 by default so it is allowing all requests. So by changing it, you will obviously have a different browser fingerprint and you can easily be identified (you would be the only Tor browser user who is blocking requests). The Tor Browser's settings are already the best they can be so I wouldn't recommend changing this.

Also, the Tor browser makes Network.http.sendRefererHeader to 2 by default because there really is no need to block requests as seen here:

When leaving a .onion domain we set the Referer header to an empty string by providing a preference, network.http.referer.hideOnionSource, and setting it to true. That avoids leaking information which might be especially problematic in the case of transitioning from a .onion domain to one reached over clearnet.

Apart from that we haven't disabled or restricted the Referer ourselves because of the non-trivial number of sites that rely on the Referer header to "authenticate" image requests and deep-link navigation on their sites. Furthermore, there seems to be no real privacy benefit to taking this action by itself in a vacuum, because many sites have begun encoding Referer URL information into GET parameters when they need it to cross HTTP to HTTPS scheme transitions. Google's +1 buttons are the best example of this activity.

Quote source: https://2019.www.torproject.org/projects/torbrowser/design/

Image source: https://wiki.mozilla.org/Security/Referrer