.js function stops (loop)

I don’t know. (are you sure it’s .id and not ._id ? )
If there’re not too many users you can try running them in parallel without the for-loop:

export async function function_in(inputs...) {
 const users = await users();
 const userOrder = await Promise.all(users.map(u => order(u.id))); 
 //userOrder will be an array with all the results
}