@Toengel: I played a bit of the first episode of The Continental and it does seem too dark. I have a 48OLED808 and when I start playing, it shows an “HDR10+ ADAPTIVE” notification.
I could only compare it to regular HDR10 on my Shield 2019 Pro, but that looked a lot less dark.
I also tried playing the first test that you linked in Kodi on the TV, and I could not see a difference between the stages. So it looks like the TV is not processing the dynamic HDR10+ metadata?
I also tried to download the second test by subscribing to the FF newsletter, but I did not receive the correct download link to the “Schnelltest Pro” file?