Today’s release of Total Cookie Protection is the result of experimentation and feature testing, first in ETP Strict Mode and Private Browsing windows, then in Firefox Focus earlier this year. We’re now making it a default feature for all Firefox desktop users worldwide.
FWIW, Total Cookie Protection was previously called Dynamic First Party Isolation and it is indeed one of the FPIs.
The name is mentioned in the Firefox Security Newsletter as follows:
Thank you for the clarification 👍🙏