I agree it's egregious, but it's quite easy to believe.
It's surely just using a standard modal and passing a string. The thing is, this is on a Mac that has scroll bars that are invisible until you scroll. It's easy to imagine testing was done other OS's where the scroll bars are obvious and the bottom line might be only partially hidden which makes it even clearer. And/or that testers never caught it on a Mac because they themselves never realized there were more.
I would hope somebody sees this now and prioritzes a Chromium bug for it. Because on a Mac at least, this is pretty serious.
(And I'm well aware this is a good example of a negative side effect of Apple's choice to make scroll bars visible by default only while scrolling.)