Ublock Origin just introduced a way to detect third-party trackers disguised as first-party scripts: Address 1st-party tracker blocking · Issue #780 · uBlockOrigin/uBlock-issues · GitHub
According to the issue it seems that it's becoming quite common for websites to use this technique to avoid adblockers detection, as you can see there is a big list of popular websites available here that are currently using this new trick: Address 1st-party tracker blocking · Issue #780 · uBlockOrigin/uBlock-issues · GitHub
Could Pi-hole implement a similar feature as Ublock Origin but for domains?
EDIT: It seems that this functionality got quite popular because Adguard is considering adding a similar feature into their app: Match CNAME records against the blocklists · Issue #1185 · AdguardTeam/AdGuardHome · GitHub and the issue from the Ublock origin github repo is currently a top post on /r/privacy: To prevent third-party trackers disguised as first-party scripts, uBlock Origin is working on a workaround based on Firefox's DNS API. This API is not supported on Chromium based browsers. : privacy.