Subscription problem

I have accessed the third-party payment Qonversion, which has been uploaded to testflight, and some phenomena such as purchase failure or purchase waiting time out occurred when the customer used it ​The Qonversion developer replied that there were too many requests for this account and needed to change the account, is that right ​Do you need to change your account? How do you return the account? I want to know how testflight can correct the sandbox account instead of its own account

Subscription problem
 
 
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