You’ve gotta take care of yourself first. If you end up getting burnt out from too many work hours alongside your academic hours, both areas of your life will suffer. Hopefully you can either get your hours cut down or take a leave of absence and come back to Starbucks at a later date (or go with handing in your two weeks). I know they probably prefer having partners with open hours rn due to the understaffing everywhere, but personally I think they need to compromise with anyone willing to come in and work. Even having an extra person for a few hours can be a blessing for taking breaks and making backups.