When obtaining the access token and refresh token for the first time using the code, the validity period of the access token is 6 hours. Within this validity period, both the access token and refresh token remain unchanged upon repeated requests. After the access token expires, the access token changes but the refresh token remains the same. Once the refresh token expires, the access token can no longer be renewed, and it's necessary to obtain a new access token and refresh token using the code again.
The question is: What is the validity period of the refresh token, and when will it change upon request?