Is it worse than Accept-Language? It's got less bits of entropy.

Is that still higher entropy when you already (necessarily) have the IP address?

225.12.3.11 sends two requests, both with accept-language nl_BE

226.4.5.244 sends two requests, one with age bracket 13–15 and one with bracket 18+

Which group is easier to track people within a (NAT) household..