Heiko-Hartwig Support has been notified about this issue. They indeed told me that the problem lies with the German banks. As bunq 's system seems to be up and running (other Instant Payments work fine) it really seems to be an issue at the other side. The statement in the support chat did bunq no longer supports synthesis banks turns out the be wrong indeed. 🙂 Let's hope that the issue is resolved asap.
🇩🇪 Support has been informed about this issue. You have actually told me that the problem lies with the German banks. Since bunq system bunq to be up and running (other instant payments work well), on the other hand, it really seems to be a problem. The statement in the support chat that bunq no longer supports these banks turns out to be wrong. 🙂 Hopefully the problem will be solved as soon as possible.