You can test it with: https://test-spenden-2.wikimedia.de/?skin=2&zahlweise=BEZ&amountGiven=100&periode=6

it seems to work.

What I do not know, is if the summary box should disappear once a user klicks on "Zahldaten ändern", changes the data on form 1 and moves forward to page 2 (right now the box is still there with the correct data). I guess it is fine to leave it like this but it is actually not needed because the summary box has its only justification for those coming in from the banner.

I am fine with both.

And the spacing between the "Zahldaten ändern" button and the text above is not according to the figma design (at least on FF Quantum)

I've modified the Pull Request to incorporate your changes, will deploy on Monday.