I believe there has been some changes made lately on pointer events.
Delta does not seem to work the same for pointer events. Here is a post around this subject.
Though in your case and since it’s working in the PG, I’m wondering if it would not work by simply calling again on the var created for the observable; on line 29 of the above example PG posted by @Naznarok :
wheelDelta = -(event.wheelDelta.deltaY || event.detail) * 60;
Can you try this? Else, you will probably need to modify according to the new behavior for pointer delta events for the camera.