Advice about Lightroom masks and "artefacts"
If you turn on the "automask" option of the local corrections brush, you are very vulnerable to enhancing any digital artefacts in the underlying image, especially but not only, along such edges. This makes a harsh boundary with blocky irrregularities. Especially this happens when working on a JPG image, or one that has at some previous point been JPG compressed. JPG compression tries to hide its artefacts so they are below the level of our normal attention, but Automask can "see" them.
One answer is to turn off automask for doing certain edges, which allows you to paint using a smooth feather. Different edges can be done in a more or less soft / hard manner depending on the brush softness, size and flow - and this allows convincing edits to be made even within defocused parts of a picture.
Another method that works well, is to deliberately paint across / beyond the edges in a smooth manner (without automask), and then to use the Erase option of the same brush, to cut back to the edge from the other side - with or without Automask as the occasion dictates.
Doing it this way, Automask is (in my experience) a lot more useful. Any imperfections or artefacts will be occuring in areas where the adjustment effect is being applied at zero vs low percentages, when you are Erasing - rather than (as your example shows) showing distracting variations between full vs partial percentages, when painting positively. Also you can correct erasing as much as you want without getting an uneven result... for example, you can make a hard edge first, and then come back with a larger radius erasing brush and automask turned off, to "feather" it back a little. Correcting and feathering positive painting, is always more difficult to do in a smooth manner.
Another way to look at that: you could be making use of the relatively even colour/tones of the non-sky items, to discriminate where the sky edge is, rather than using the highly variable colour/tone values that sky edges tend to accidentally exhibit.