Javascript error on payment option selection

We have got a D10 installation with the latest beta of this module. When Klarna payments is chosen as payment method, the klarna-mount is present and rendered.

After click on one option (eg. "pay now") a javascript error is thrown.

klarna.js?sg1yex:2 Uncaught TypeError: Cannot read properties of null (reading 'insertBefore')
    at s (klarna.js?sg1yex:2:5870)
    at Object.update (klarna.js?sg1yex:2:5985)
    at klarna.js?sg1yex:2:12949
    at Array.forEach (<anonymous>)
    at Object.update (klarna.js?sg1yex:2:12935)
    at klarna.js?sg1yex:2:3160
    at klarna.js?sg1yex:2:5465
    at Array.forEach (<anonymous>)
    at Object.update (klarna.js?sg1yex:2:5453)
    at klarna.js?sg1yex:2:12949

We use this module (2.x) on a different project and everything is working fine there (thats drupal 9 still). We noticed that also the API credentials of klarna changed quite a lot. Where the old one has a quite short password and a username starting with K..._.... the new one has a very long password which starts with klarna_live_api_ and the username is an UUID. Maybe there is also some kind of confusion on that level.