After successful authorization, the next day the user can not send data to strava synchronization

You should get some kind of error message if refreshing the token fails. That message should give you some insight into what is going wrong.

Also make sure your refresh request is following the OAuth spec. I know your mentioned you read the documentation, I'm just linking to it in case anyone else is reading this - https://developers.strava.com/docs/authentication/#refreshingexpiredaccesstokens

Thanks for your answer, then the code returned when I refresh the expired access token is 400 How do I need to find out my code error.

HTTP 400 is bad request.

Finding the error message will depend on a lot of factors such as the platform you are using, any OAuth library you are using, etc. It's hard to tell you exactly where to look. You need to look at the full response wherever you're seeing the 400 status, there should be more information there in either the headers or the response body