IOS application via testflight returns SSErrorDomain error 100 during receipt update

Question

I installed my application on friends' iPad through Testflight. The installation was in order, and even updates were sent properly.

Today he launched the application for the first time. I check if receiving the application is correct as a prerequisite for a later purchase of the application (IAP).

If the receipt is incorrect or not on the device, I start the update. Apple usually asks for the iStore ID password. But instead of receiving, I get the error message The operation couldn't be completed. (SSErrorDomain error 100.) The operation couldn't be completed. (SSErrorDomain error 100.)

Is this some feature of Testflight?

Everything works flawlessly when deployed to my iPhone directly from Xcode.

Thanks for your thoughts in advance.

UPDATE: I use Apple TestFlight and was able to try it myself. After installing on the device, updating the check gives an error. I can make an in-app purchase without a problem, and the receipt I receive is correct and the error goes away. But as soon as I start another check update, even with the completion of IAP, the error appears again ...