alt Hacker NewsYou can't gaurentee any of this is fingerprintable without checking twice (i.e. give the user a unique url, then ask them to restart the browser and visit it). In privacy browsers like LibreWolf or Mullvad Browser this is almost all spoofed, save for things like the IP which needs to be hidden/changed independently of the browser.
Correct on rigor. Proving a fingerprint requires the two-visit protocol you describe. The page doesn't actually compute a stable fingerprint or attempt to track returning visitors, it shows you the signals that go into one. The barcode at the bottom is deterministic from the data shown but isn't compared against anything stored. Sloppier than a real fingerprinting tool, by design.