The domain smartproxy.dataunlocker.com is cloaked with CNAME and is a tracking proxy. See this entry in uBlock Origin's assets for reference. Here's an example website: https://woodbrass.com/. It uses the domain 1bw7etm93lf.www.woodbrass.com to cloak tracking requests. The subdomain is random and might change, but doesn't do so very often. (Dataunlocker's website mentions this). It would be nice if it was added as a host for blocking though DNS.