We using the standard Magento 2 PayPal integration.

On the production site of our customer, we get an Javascript error "window.paypal.ThreeDomainSecure is not a function", and payment cannot continue.

This happens when trying to place an order with the inline VISA form on the Checkout (not when using an existing paypal account).

It also happens only on production, so we cannot reproduce that locally yet with the sandbox account.

We cannot find this line of code in the Magento code, so we believe the error comes from the components loaded from PayPal

Did anybody see this issue before and knows a solution or how to narrow it down?

Is it likely to be related to the PayPal account or a technical issue?

A bit debugging:

[![error message][1]][1]

Somhow the module seems to be there? but cannot be accessed

[![window.paypal][2]][2]

It seems to come all from PayPal? So no Magento issue?
Can it be due to some server config?

[![script source][3]][3]

[![error message][4]][4]

    window.paypal.ThreeDomainSecure
    undefined


*EDIT* is it maybe related to CSP blocks? Can I even influence that? The checkout.js mentioned is also loaded from PayPal.

[![CSPerrors][5]][5]

*EDIT* it seems to be related to the PayPal account, as we cannot reproduce it with a sandbox account. There is a PayPal support case open, still we try to rule out issues on our side.

  [1]: https://i.sstatic.net/JG9wv.png
  [2]: https://i.sstatic.net/1aRMG.png
  [3]: https://i.sstatic.net/kskUn.png
  [4]: https://i.sstatic.net/XOrEo.png
  [5]: https://i.sstatic.net/Fbzen.png