I have a lot of free members. Fetching the /api/oauth2/v2/campaigns/<id>/members gives me a very huge list, though I only need paying patrons. Is there any way to exclude the free tier from the API response? Thanks in advance.
There is no official way to do this. You would have to fetch all of your members and filter through. Depending on what relationships you fetch, the members API can return a list of up to 1000 records.