the individual behind that link has trolled sony raw compression all over the internet, but last i heard he's never been able to actually re-create the problem himself... that star trail shot, for instance, is not his.
which should tell you how often it actually happens.
no question that raw compression can show very minor issues in extremely high contrast areas, visible in underexposed shots that have been seriously overprocessed... long-exposure lights against black night sky, for instance.
Sony A7R teams up with Canon glass shows it in his review, with extremely overprocessed shadow recovery, but the dr/file latitude of the sony sensor completely blows away canon's sensor, so which would you pick? the canon 5dsr sensor has the same weak dr/latitude issues.
"...Some chicken littles cry out that the sky is falling and that they would never buy a camera that does this.
Well, not so fast. If you look at examples that have shown up online, what you’ll see is that the net effect in real world images is de minimus. Can you see it in some images, some of the time at 100% on-screen? Yes. Have I ever seen this be an issue in any image that I have ever shot with a Sony camera? No, I can’t say that I have. ...I for one am not giving this a moment’s further thought as I shoot with my Sony A7II and new A7RII.
Frankly, if I had to choose one over the other(Pentax 645Z vs. A7RII) I’d go with the A7RII. https://luminous-landscape.com/sony-a7rii-review-and-hands-on-report/