Hi Markus,
Great image, well done.
As Nathan said, if you go pixel picking you can see processing artifacts around the stars. I’ve had this happen too and it’s from using the High Pass Filter. You could try using Minimum instead set at between 0.3 and 0.8 pixels with maintain “ roundness “ selected instead. It has a similar star reducing effect but with more control. If you have the preview set on a good section of nebulosity and play around with the pixel size and go as close to 0.8 as possible before you start seeing blotchiness in the preview pane.
I hope this helps. You’ve got great data there. Good work
Ryan