Firefox 86.0 and cookie management

Firefox 86.0 has just been released. It includes an interesting tweak to cookies management: " Today, Firefox introduces [Total Cookie Protection] to Strict Mode. In Total Cookie Protection, every website gets its own “cookie jar,” [preventing cookies from being used to track you from site to site]."
More info here:

I actually started Firefox (and got an update reminder) because Safari 14.0.3 is irritating me. Often when it starts the Bookmarks and History take ages to load (OK 1 minute seems like ages!). This does not happen with synced bookmarks on my iOS devices or a Macbook. I don’t have any plug-ins or extensions running. It is a puzzle.