IIRC, VOY and DS9 were stored for long term on videotape, with the original footage deleted from the disks, while TOS and TNG were still (kept on) reels. Remastering film is a lot easier than upscaling low quality videotape, especially since that is also vulnerable to EM and much more to heat than modern film. I think the Laserdiscs were created from the original footage, so you have some proper gold here. You might be able to create even better upscaling with this than CaptRobau: …blogspot.com/…/how-did-i-upscale-star-trek-ds9-f…
I think they were all on reels. The DS9 doc a couple of years back (after than blog post) had 4k hdr widescreen rescans of select scenes for the campaign bonus on kickstarter. Truly amazing. They also had the CGI files to rerender some scenes like Sacrifice of Angels battles.