There's a bright highlighted warning that says "STOP! Only proceed if you arrived this page by scanning a login barcode at google.com. Otherwise, do not proceed

There's a bright highlighted warning that says "STOP! Only proceed if you arrived this page by scanning a login barcode at google.com. Otherwise, do not proceed!" Will users read the warning? I would—and did—it really grabs your attention given the fact its background is yellow and takes up so much of the iPhone screen. I suppose there are probably other safeguards as well, given that this is Google—maybe timed expiration?