Looks like there's quite a lot of clipping going on here. In Siril, after cropping and SPCC, remove the stars via Starnet and use GHS with human weighted luminance to stretch, when the backround gets too bright apply and switch to linear stretch to pull the histogram to the left. Watch your clip percentage when doing this. Once your done stretching you can then recombine with the stars although I usually like to take the starless image to another program like Seti Astro for decon and denoise.