Do I need remove adRequest.addTestDevice in production?

Question

The document does not specify it. I thought we do not need to remove it, because it is our unique device id, the other devices with different id are not impacted. But it is

Answer 1

That is correct. When your application is run on a device with that deviceId it will get test ads. All other devices will receive real ads. So you can leave the config in for production.