Nicloks

I would try to replace the fringing with another region of the sky.
You can use these dark halos to your advantage. They will allow you to create a mask of the fringing.
Add a defring live filter, make those halos really black and change the blending mode to differece.

Improve the "mask" by adding a B&W adjustment.

Duplicate your background (BG Copy) and right click on any of the RGB channels and choose "Load to Pixel Selection".
Expand the selection (Select > Grow/Shrink) by 1px and add a layer mask to your BG Copy.
Turn off the visibility of B&W adjustment and defringe live filter.

Finally, with the Move Tool, move the BG Copy to the left. Just make sure you have "Lock Children" active, otherwise the mask will move along with the layer.

When creating a new stack the layer order is pulled into Affinity Photo in descending alphanumeric order based on filename.
There is currently no way in Affinity Photo to alter this order by layer selection en masse which creates a significant hindrance to workflow where many dozens of layers are in use.
Would like similar functionality to PhotoShop where the user can select the layers needing a different sort order, then selecting the "Layer" menu, "arrange" menu item and then "Reverse Order".
Assuming something like this would be best suited under the "Arrange" menu and would allow the user to sort their selected layers in ascending or descending order.