Token Refresh return 400 & 200 alternately

[snappyrain]

When I refresh the refresh_token through
https://auth.tesla.com/oauth2/v3/token according to the documentation in https://tesla-api.timdorr.com/api-basics/authentication,
Sometimes it returns status code 200, while sometimes it returns status code 400.
Is there something wrong with the back end of Tesla?
It really confused me.

My request body is like below.
**NOTE: infomation below is just for example. Tokens are fake. **
{"client_id":"ownerapi",
"client_secret":"c7257adc64034f9419eabc033b093bb2fa3",
"grant_type":"refresh_token",
"refresh_token":"eyJhbGciOiJSUzI1NiIsIafcWR6eUR4MHh4OCJ9.eyJpc3MgvdF1dGgyL3YzIiwiYXVkIjoiaHR0cHM6Ly9hdXRoLnRlc2xhLmNuL29hdXRoMi92My90b2tlbiIsImlhdCI6MTY1ODg0Nzk5OCwic2NwIjpbIm9wZW5pZCIsIm9mZmxpbmVfYWNjZXNzIl0sImRhdGEiOnsidiI6IjEiLCJhdWQiOiJodHRwczovL293bmVyLWFwaS50ZXNsYW1vdG9ycy5jb20vIiwic3ViIjoiOWNlN2I2MjgtZGZhZC00NDY4LTliZGQtN2MwMTFhY2NlYTBjIiwic2NwIjpbIm9wZW5pZCIdvc3MiXSwiYXpwIjoib3duZXJhcGkiLCJhbXIiOlsicHdkIl0sImF1dGhfdGltZSI6MTY1ODg0Nzk5N319.O0x9t4-1h0zpYzfP0_55aFYw_D1IZBDcq8Crpa1f7Ybk-OZTkZIVbhglNi6uktEoFulg1y6O2x9sVYsfz56w-xYQ8mALchYGj9x8NnBMM4IsPpvkA1fxgBkS1ANyx3X7S8ucJWJYJYJFz2NHJCTdmIkAkT0RNrjp-bzL-qD7UL-k3H3NNoWFCCKmHEj8T0n332vYOaBj-qsD",
"scope":"openid email offline_access"}

and headers:
User-Agent: androidKotlin
Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpSfDWR6eUR4MHh4OCJ9.eyJpc3MiOiJodHRwczovL2F1dGgudGVzbGEuY24vb2F1dGgyL3YzIiwiYXVkIjpbImh0dHBzOi8vb3duZXItYXBpLS2F1dGgyL3YzL3VzZXJpbmZvIl0sImF6cCI6Im93bmVyYXBpIiwic3ViIjoiOWNlN2I2MjgtZGZhZC00NDY4LTliZGQtN2MwMTFhY2NlYTBjIiwic2NwIjpbIFMiXSwiYW1yIjpbInB3ZCJdLCJleHAiOjE2NTg4NzY4MTcsImlhdCI6MTY1ODg0ODAxNywiYXV0aF90aW1lIjoxNjU4ODQ3OTk3fQ.5-cmKI2e_RMJOS4VPRw6gkcFnAgqfBoDBZZcwYnRjgzkvc-RX-tHKOSlDWotqUDOWgSmnYfEGDJBVxOtVugpjGoI-tUanRjsJPoCF_YTH9yOybwRkLbPxsY9WceFER6f5W2b5wJUxKldyF94Qkdqb-CnBVrehBeUACRDIw1bBkCY-wFe_hRE9i4Z-pRk6o763oyTcNbes2Ot1nJ_8o8VzmJz2iXoVPhI_fp2MpHG2e9FnC2IwYhA

Any help would be appreciated. Thanks in advance.