When i try to create a subscription using API, with starting date in past, i get following error:

Request:

POST /subscriptions

[
  "customer_id" => "xxxxxxx"
  "plan" => array:1 [
    "plan_code" => "xxxxx"
  ]
  "starts_at" => "2020-12-06"
]

Response:

{"code":8006,"message":"Please specify a valid card."}

Why do I get this error ?