There is a difference between children in it and characters such as Felt, Beatrice, certain witches and that music girl last season. It’s not that they’re sexualized but an implications towards it such as Subaru being called a “lolimancer” or implicating that they cling with feelings toward him. I’m not saying it’s wrong but it makes me feel a little weird when watching.
Imo most can be explained Felt is just a child, plain and simple. She needs to be immature bc she’s a rebellious teen who is on track to become the ruler of the country Beatrice isnt a child but a spirit- but in all purposes is still a child. Subaru actively calls her his daughter, and she pretty much accepts that role, no romance involved ay all I cant talk about patra bc spoilers but its just a childhood crush