Many of the ad serving SDKs slurp up all this data anyways and send it down using a request body, query string, or something that isn't the "Referer" HTTP heade

Many of the ad serving SDKs slurp up all this data anyways and send it down using a request body, query string, or something that isn't the "Referer" HTTP header. I'm not sure how ad verification providers get this data, but if anything it's just going to mean less information leaking out from systems like DFP to the smaller ad tech firms. But firms like Google will still be able to figure out what path you were on.