Firefox and Safari have been progressively limiting what third-party cookies are allowed over the past seven years.

i thought so to, but it's not like that. of you open that article:

title: "Today’s Firefox Blocks Third-Party Tracking Cookies and Cryptomining by Default"

from the text: "...will block known “third-party tracking cookies” according to the Disconnect list."

so basically they have a blacklist of third-party cookies, and if it is not on the list it is allowed.