Adding the TabViewStyle doesn't fix the problem, so it really looks like a watchOS 9 bug. I created the same project with Xcode 13.4.1 and watchOS 8. There everything looks fine. I have now create a feedback (FB11028017) Thanks for you help anyway.

It’s fixed for me. Have you tried it on a device or on the simulator?

My solution was to upload the file to a web service and share this link, not ideal, but afaik sharing files via watchOS isn't possible.

I would like to do exactly the opposite, convert a group into a folder.