When Facebook users click on a link that points to an external website, they’re presented with a warning that reads, “This link might be malicious. Please follow it with care.” It turns out that the same security warning is shown even if the site you are about to visit is facebook.com.
This interesting aspect was noticed by a Hacker News user. As others have pointed out, the warning message appears for all URLs, even ones that point to sites that don’t exist.
However, it’s worth noting that some domains, such as facebook2.com, which the company doesn’t own, are blocked completely (see screenshot) to protect users against phishing attacks. This means that the company is checking the domain name of the website that’s about to be visited.
This is why the fact that facebook.com is flagged as a potentially malicious website is even more interesting.