Not practically, no, since the approach is the same as setting the Referrer-Policy header to strict-origin-when-cross-origin. In most cases it can't be reliably

Not practically, no, since the approach is the same as setting the Referrer-Policy header to strict-origin-when-cross-origin. In most cases it can't be reliably deduced whether a visitor legitimately came from https://reddit.com/ https://reddit.com/ (from the root origin) or some path on https://reddit.com/ https://reddit.com/.