Facebook tests a feature that gives you information about the (suspicious) accounts that come into contact with you on Messenger.
Since 2016, Facebook has been cleaning up on its platform. And in addition to the many efforts to remove fake accounts and to reduce the visibility of misinformation articles, the company is also working on a new feature on Messenger that helps the user identify suspicious accounts that Trying to get in touch.
This new feature is to give some contextual information to the user when contacted on Messenger (by an account that could be malicious).
For example that Messenger reports that the account that sent a message was created from a Russian phone number, that the account was recently created (which might suggest that it is a fake) and that this account is different from that of a friend on Facebook who has the Same name (suggesting a spoofing of a friend's identity).
With this information, Facebook could better protect its users. Indeed, in addition to the propagation of fake news, the mail service is sometimes also used to scam users. For example: Impersonating someone, then asking for money or sharing a malicious link.
Facebook confirmed this test, explaining that it is trying to "test a way to provide people with more context on people with whom they may not have connected yet."