Giving your chickens some extras -- including a few oats -- is fine, but generally speaking you don't want the treats to overwhelm their normal feeding, as they risk not getting enough protein and some critical nutrition. Oats, in particular, are not terribly nutritious.
I'm not sure if the giant bowl is something you store your treats in, or if it is sitting in the run. If it is sitting in the run, I wouldn't recommend that. Limit the treats to a handful or two (depending not the number of chickens) and scatter it about their run, so they have to work a little to find it.
The general rule is to keep treats to 10% or less of their total intake. I would also mix in some type of high quality protein into the treats, like black fly solder larvae or mealworms, as that will help keep the treats a little better balanced on the protein and related nutrition scale.