I'm with JA on the baffle misalignment
fwiw (since I don't have an RC8), some opinions re the stars;
The star test pattern looks nicely symmetrical, but you may need to take it closer to focus to see if there are any misalignment or figure errors. In case you haven't already used it, this is a good resource for faults and star testing.
https://www.telescope-optics.net/dif...berrations.htm
Apparently, collimating these things is an art. If you haven't already seen it,
https://www.iceinspace.com.au/forum/...d.php?t=120591 edit. Just read your earlier thread on collimation - pity the secondary dot is missing - I would be putting one on the mechanical centre of the secondary and using it with your TS device to collimate the scope as per the video..
The dim stars are tiny and the nebula is really well resolved - you had good seeing and the scope is functioning well enough to get most of the energy where it is needed.
The intermediate stars have a slightly trefoil type halo, which is a bit asymmetric . suggest that you look at the mirror mounting systems - trefoil generally means that something is distorting one of the mirrors in 3 places. maybe the adjusting screws are so tight that they are distorting the secondary plate a little? I don't know how the primary adjusters work, but could they be so tight that they are distorting the mirror?
The bright star has a distinct diffraction pattern - the pattern looks large and may be zonal or spherical aberration. I guess this might result from misalignment not properly correcting SA? If you can't find any pinching/distortion anywhere on either mirror and the scope is properly collimated, then the error is in the optical figure of an element.
The spyder diffraction pattern shows what is probably strong secondary diffraction from the end mounts of the vanes. You will have to live with this unless you can modify the mountings to get the big end brackets out of the light path (assuming that is the issue)
Despite all of this, you are getting really nice detail on the nebula and the scope is obviously working pretty well. The stars maybe look a little unusual and definitely could do with a tidy up, but the nebula is the thing that matters - even if you have to accept the current level of performance, you still have a useful imager. Professional telescopes can have stars that are a bit untidy - and it doesn't seem to matter too much.
https://esahubble.org/images/heic2018b/.
https://esahubble.org/images/heic1903a/
Cheers Ray