Unfortunately, lots of treats cause build up of fat around the internal organs, she respiratory system or heart might have given out.Well usually the treats are almost daily if they are produce scraps, mealworms a few times a week at max. It is possible if she found something toxic or moldy as the previous owners left random objects scattered across the yard which we find as it is unburied/ or in plain sight and we throw it away. They have had a lot of scratch grains in their food lately, but mostly they've been foraging
But it's impossible to day without necropsy