I'm not the parent poster, but I worked in ad tech. With third party cookie policies getting more stringent, many websites now use either a reverse proxy withi

I'm not the parent poster, but I worked in ad tech. With third party cookie policies getting more stringent, many websites now use either a reverse proxy within the first party domain that points to third party servers, or they use a first party subdomain that points to third party servers. In either case, it allows the servers belonging to the data gatherer to appear as first party, thus getting around third party cookie restrictions. Combine that with browser fingerprinting, and you now have a harder but very viable way to replace the functionality third party cookies previously had.