Devise Registration controller, every parameter seems to be removed

trying to override Devise Registration controller, following a couple examples online, but for some reason every parameter passed in seems to be removed. this is the controller.

class RegistrationsController < Devise::RegistrationsController

  skip_before_action :verify_authenticity_token, :only => :create

  def create

    p sign_up_params

    build_resource(sign_up_params)
    resource.save
    sign_up(resource_name, resource) if resource.persisted?

    render json: resource
  end
end

this is the request

curl --location --request POST 'localhost:3000/buyer_users' \
--data-raw '{
    "buyer_users": {
        "email":"peter245@email.com",
        "password":"123123123",
        "site_id":"103eb514-8185-4820-8f16-3a9d082c5f60",
        "account_id": "f362189f-a843-4c19-927a-845ce2cb0ad0"
    }
}'

we seems to be picking up params, but everything is removed

21:16:05 web.1         | Started POST "/buyer_users" for ::1 at 2022-05-06 21:16:05 -0700
21:16:05 web.1         | Processing by RegistrationsController#create as JSON
21:16:05 web.1         |   Parameters: {"{\n    \"buyer_users\": {\n        \"email\":\"peter245@email.com\",\n        \"password\":\"123123123\",\n        \"site_id\":\"103eb514-8185-4820-8f16-3a9d082c5f60\",\n        \"account_id\": \"f362189f-a843-4c19-927a-845ce2cb0ad0\"\n    }\n}"=>"[FILTERED]"}
21:16:05 web.1         | {}
21:16:05 web.1         | Completed 200 OK in 7ms (Views: 0.1ms | ActiveRecord: 0.0ms | Allocations: 1155)

routes are set up like this

  devise_for :buyer_users, defaults: { format: :json },
             controllers: {
               registrations: 'registrations'
             }

EDIT: after debugging some more it seems that the entire parameter is taken in as 1 string.

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