On any Stack Exchange site front page, when mouse hover on the hot tab, the tool tip says:
Questions with the most views, answers, and votes over the last few days
And the questions are indeed displaying for the last few days.
But in the browser title it shows Hottest Questions Today, actually it is not showing only the hot questions of today, for the last few days questions.
So for the hot tab the browser title need to be change according to it's tool tip content.