Some applications call with error message: SING_FAILED, is the Cloud Authorization key created before still valid?

If you have applied the Cloud API key, it is still valid, Tuya will not limit your cloud api request ability for the time being. It is recommended that you use the cloud api key to call Tuya to open the api for verification. At the same time, the Tuya cloud api key is only used for cloud integration solutions, meaning that this key can only be used for Tuya applications to call the Cloud API.