Not allowed eat out during breaktime can only takeaway food and eat in workplace is this normal?

Working in retail currently and apparently I’m not allowed to eat out during break-time and can only dabao food and eat in the store pantry. Is this even normal? I can’t have any personal space and break from work mentally. The manager can just call me anytime during the break just to go back to work if the store get too busy due to their lack of manpower should I just throw letter and change job??