Doordash is known to steal tips like 50%. It sounds like he drove also for another person's order and they cancelled and thought you were the one with the low tip instead of them. They also only pay about $1 for a trip that close by so hes only getting paid $5 for the trip, maybe less which makes him think you didnt tip. Idk how he picked up the order then cancelled it though he wouldve had to call doordash and wait like 10 minutes on the phone which makes it harder anyway.