Get a count of subscriptions that are currently active on your account

curl --request GET \
  --url https://api.twitter.com/2/account_activity/subscriptions/count \
  --header 'Authorization: Bearer <token>'

{
  "data": {
    "account_name": "<string>",
    "provisioned_count": "<string>",
    "subscriptions_count_all": "<string>",
    "subscriptions_count_direct_messages": "<string>"
  },
  "errors": [
    {
      "detail": "<string>",
      "status": 123,
      "title": "<string>",
      "type": "<string>"
    }
  ]
}