Personally, I think worth fighting. If not for you, then to help that landlord understand so they don’t do it to someone else. It’s possible they know exactly what they’re doing, it’s also possible they don’t.

Plus $50 is like a weeks worth of lunch.

They can’t keep the whole deposit if you don’t pay. They have to show exactly why they are withholding it. Request a move out walkthrough AND take video of the entire place so when they do send your deposit back, you agree with what they are withholding and for what.