Google Foobar is a secret way of recruiting top developers and programmers from around the world. It includes challenges occurring instantly on the screen of the developer when they search for some specific keywords related to coding. You may find it surprising that it only comes on Chrome and no one is aware of the criteria on how and when it will appear on your screen. However, the silver lining of the secret hiring process of Google is that it provides direct interviews to the developers and programmers who clear all the levels of this challenge.
~ https://www.turing.com/kb/foobar-google-secret-hiring-technique
I did the challenge in year 2017. Safe to say, no one reached out to me .
IMO, the challenge doesn't matter for hiring purposes. It's more of an intellectual exercise you do for fun now since all the answers are online.