Fake flexible work hours

Just wanted to rant. Been working for a company for a few months now. Upon onboarding they told me if you have no more pending work for the day, you can leave early. Similarly, everyone has been doing this. Earlier today, I left work early since l've been in the office since 7 am for a meeting. President of the company sees me going home and reprimands me... proceeds to embarrass me in front all of the department heads for it too. The company doesn't even have a sign in or sign out... why am I the only one being embarrassed for it???? Flexible working hours my ass. Maybe corporate just ain’t for me… They tell you one thing then expect something else.