This article is helpful:
https://sg.theasianparent.com/gauging-how-much-formula-your-baby-needs
Limit your child's milk intake to 16 ounces (480 milliliters) a day.
Include iron-rich foods in your child's diet, like meat, poultry, fish, beans, and iron-fortified foods.
Continue serving iron-fortified cereal until your child is eating a variety of iron-rich foods (at around 18–24 months old).
Is LO eating enough other than milk because maybe that’s why he wants more...
Does he drink milk in the day or only at night?
perhaps also it has become a habit that he wants milk to sleep.
Think should look into his overall intake and perhaps then it’s easier to determine whether it’s too much. However 3rd round and totalling about almost 500ml
That is abit too much at one go I feel.
Try adjusting the environment, dark room, warm bath, pjs and then coax to sleep after milk.... could increase slightly the first feed to 300ml and when done.... encourage to sleep by lullaby’s, patting etc