I fixed it by not using UIViewController on the page.
Don't know that was the exact problem though since the view was dismissing at seeming completely unrelated timing.
The issue first appeared more than 3 months ago.
https://forum.unity.com/threads/project-wont-build-using-xode15-release-candidate.1491761/#post-9341597
I guess both the Unity and the Xcode developers have no intension to fix this..
I posted the issue to the Flutter repo.
https://github.com/flutter/flutter/issues/138938
I fixed it by not using UIViewController on the page.
Don't know that was the exact problem though since the view was dismissing at seeming completely unrelated timing.
The issue first appeared more than 3 months ago.
https://forum.unity.com/threads/project-wont-build-using-xode15-release-candidate.1491761/#post-9341597
I guess both the Unity and the Xcode developers have no intension to fix this..
I posted the issue to the Flutter repo.
https://github.com/flutter/flutter/issues/138938