First try with UNC254 and new camera

Camera: ASI294MC Pro
Exposure time: 30 seconds
Gain: 360
Stacked pictures: 30
Darkframes: None (darkframes were glitchy. some light still entered...)
Flatframes: 10
Processing: PixInsight
Location: My Balcony

Distortion is gone now, due to correct distance between GPU and camera sensor.

First try with new setup (UNC254)

Camera: Sony Alpha 5100
Exposure time: 300 seconds
Stacked pictures: 3
Darkframes: None
Flatframes: 10
Processing: PixInsight
Location: Sternenpark Westhavelland - Star park, region with low amount of light pollution

You can clearly see the distortion at the right side of the image. This is due to incorrect distance from GPU to camera sensor. (roughly off by 10mm)