https://www.bleepingcomputer.com/news/security/mozilla-flooded-with-requests-after-apple-privacy-changes-hit-facebook/

Mozilla volunteers have recently been flooded with online merchants and marketers' requests for their domains to be added to what's called a Public Suffix List (PSL).

Public Suffix List (PSL) is an initiative of the Mozilla community volunteers to maintain a list of top-level domains (TLDs) and domains that should be treated as one to prevent the mixing of cookies between distinct domains.