Silly question, but did you take dark frames in the below images ?
The speckling can be noise from the raw image, or maybe an artifact from stretching too far during processing.
Either way, more subs and dark frames will definitely help reduce it.
This was my Andromeda that weekend with Canon 1200D and 250mm Lens. I can't remember if I cropped this a bit. But plenty of background noise due to lack of subs. I think this was 5 subs at 5min each. Sensor temp around that 30-35 degrees also.
The amount of detail you captured in Orion though is awesome. Nice Job.
