Lightroom/Camera Raw: Artifacts on edges caused by clarity

Here's  a try at creating the same toning and color with Clarity +35 and Dehaze +35:

Whether clarity is above or below 50, the artifacts are always there. They might just not be as strong. And as you mentioned before, also other options introduce them, like for example "shadows".

I by the way also noticed these artifacts on raws of my old Pentax K100D if I switch them to process version 2012.

Well, I never really got to like dehaze. It might work well for images that are really foggy/hazy but apart from that I find it quickly introduces clipping in the blacks. On top of that it's currently not available to people who purchased Lightroom 6. Clarity does do something different and it can be very useful for many images, at least if applied moderately. Yet I have to say that I would also have appreciated it if the old clarity option had been maintained; it really just is something differnt. Or, as an alternative, Lightroom should start offering a real unsharp mask filter with radii above 3.5px and that allows multiple ones ones to be applied on top of eachother. However, this is kind of off-topic.