I was in contact with Swish support the other day (2024-10-28) and this is what they wrote:

We are working on a change that will solve this issue with Azure but are not quite finished with it. We have also received indications from other merchants that by changing "payment plan" in Azure they have been able to make it work again with calls toward Swish API's. Unfortunately we do not have any insight into how exactly this is done.

So I guess they are still working on a fix for this issue..