Typescript ui - not returning to application

I created a non-default organization and defined a project and application inside. The application is an open source application which supports oauth2 and also works with zitadel, when using the default organization (docassemble).

Now I wanted users to be able to register themselves in the non-default organization using the typescript ui as the native zitadel ui does not support this.
Registration and logging in to the organization preset in the ui (via environment variables in vercel) worked.

Then I wanted the target application to use the ui for logging in to zitadel, so I changed the url in the configuration of this application to use the vercel domain of the ui instead of my zitadel domain. This causes an error in zitadel stating that the domain used by the ui is not trusted.

At first I thought I had to add the domain to my organization under "verified domains", but a "trusted domain" can only be added via the API. After doing this with the v1 API, now I am being directed from my app to the ui page, but after logging in, I am not redirected back.

Am I missing something or is the typescript ui not supporting this yet?

Zitadel has version 2.63.4, the typescript ui is from last week.