I get some banding in Photoshop when I auto-blend (RAW) layers. Is there a way to overcome this?
Below is a cut-out from my panorama.
duplicate the image into two separate layers the first layer blur the layer until there isn't any banding; since there isn't any stars or objects in the sky. then drag that blured layer below the unedited layer. using the eraser tool use a softer brush and gradually erase bottom to top. that should help with fix the banding and also make the image look sharper.
I have occasionally understood the problem which you get. You have a slight variance of material at edges of photos and Photoshop is making hard transitions between exposures what results in posterisation.
There is a way of overcoming it but it seems to be non-automatable to me.
2.1 select the layer
2.2 ctrl+click thumbnail of layer
2.3 create pixel mask
2.4 select "feather" in "masks" tab big enough for you
IIRC, Photoshop creates a mask for each layer so you might only need to set feather for each layer. 2.3 and 2.4 can be recorded and assigned to a hotkey.
P.S. Your usage of term "blend" confused me. I hope that I understood you correctly now.