Sky masking causing fringe on the horizon

Hi, I've got a bunch of images taken outside with a rolling hill in them. Two things break this hill: the subject couple (wedding image) and a dead tree.

I did a "Select Sky" mask in Lightroom Classic and wanted to make the clouds more dramatic (as they were at the time). Now I could lower the exposure, or highlights, or whites, or dehaze - or a combination of all of these. Indeed that's what I did - a combination.

The problem is that the mask selects a little bit of the top of the hill so when you lower anything you get a bit of a "ring edge" or "fringe" to the hill (it is less noticable around the couple themselves).

I've tried only adjusting one of those things at a time and the issue remains much the same.

Before:

After - note the "double line" of the horizon.

Before:

After:

I know it's the mask as when I simply lower the exposure dramatically I can see the effect well - it must be selecting part of the hillside and/or feathering and including the hillside.

Any idea of a quick fix as I've got a couple of dozen like this to work on?

My best attempt so far is to use a big soft brush to run along the divide and deselect some of the bottom of the sky but that means it gets bright at the horizon which isn't ideal.