Firefox uses a built-in domain blocklist for tracking protection, in addition to blocking third party cookies

Although that would not explain why Chrome and Opera pass that at all to begin with IMO. Maybe these browsers enforce their own additional data silos or other deviations from specs when in Private Browsing mode. I know Chrome for example shrinks the storage provision for various JS APIs down to practically nothing when in Incognito mode, which can break things like Teams Web etc when you start sharing files.

Either way though all marketing ever is, is just a selection of carefully chosen words. In this case, browsers too, as there's no Brave there (I'm not a fan of Brave anyway, but worth noting)

Precisely why these "feature comparisons" are bogus.

It's this.

Firefox' total cookie protection does not block third party cookies, it isolates them in separate jars for each website....

Total Cookie Protection works by creating a separate “cookie jar” for each website you visit. Instead of allowing trackers to link up your behavior on multiple sites, they just get to see behavior on individual sites. Any time a website, or third-party content embedded in a website, deposits a cookie in your browser, that cookie is confined to the cookie jar assigned to only that website. No other websites can reach into the cookie jars that don’t belong to them and find out what the other websites’ cookies know about you — giving you freedom from invasive ads and reducing the amount of information companies gather about you.