Gameloft Asphalt 9 - Paypal Login Problem - Endless Loop

[Schlemihl]

When trying to make a purchase in Gameloft Asphalt 9, the following problem persists:
on my android device (Software Version Android 9, One-UI-Version 1) I successfully complete the 2FA.
Then, for a few seconds, it seems to forward to the account page. Then the login page is displayed again.
This is and endless loop until I stop the attempt. Hence, no payment is possible.
Very disappointing.

What I have tried so far:
updating the software, updating the Playstore, updating the app, restarted the device several times and cleared the cache. To no avail.
Called PayPal support but they could not help, as no failed payment attempt is recorded. 

Does anyone have a similar problem or a solution to this?

[Schlemihl]

As stated before, I had already spoken to PayPal Customer Service several times. However they were not able assist with this problem as no failed payment attempt is recorded.
It seems to be a technical problem related to the vendors shop integration with PayPal. I spoke to Gameloft and PayPal support but none of the staff I spoke to could offer any help with this so far.