Nothing to do with the enclosure size and yes there is such a thing as an enclosure being too big.
Many BP reach a plateau when reaching 800/1000 grams my advice keep the animal in the smallest enclosure possible to help the animal resume feeding, no handling except for maintenance.
I have had many female that had stop eating at that range and they only resume feeding (or at least resume faster) when place in smaller, dark enclosure.
I currently have a 1000 grams female that had to be downsized to a 15 quarts as she will not eat for me in a 32 quarts tub, after 2 weeks in her new tub she finally ate for me (she has been with me since October and never took a meal for me)
With Ball Pythons it is all about security and trying to mimic their natural environment as much as possible, in the wild they spend 80% of their time in tight dark termite mount and being able to provide security is essential.