Appreciate it! I'll probably just try to track down the original versions. I've meaning to dive into the Star Trek world for years now. I don't know why Paramount doesn't just give you the option to watch either.
The only changes are those orbital or space shots being done in CGI and cleaning up some effects shots to be more consistent or not be so obvious now that they're being viewed in HD
I don't think it's worth finding original broadcast versions. The CG space stuff is generally done in a way that makes it still feel appropriate to the original 60s aesthetic and just addresses the fact that a lot of those early effects shots resulted in muddy, boring planets that were badly composited in the background or had trouble showing ship models doing anything beyond the most basic movement. Otherwise I think the only other sort of common changes were things like removing visible wires from "floating" objects and fixing badly blended effects overlays.
This isn't a Star Wars situation where Lucas inserted a bunch of CGI crap that altered shots or changed the composition of scenes. It's just cosmetic touch-ups to stuff that was already there and I don't think it distracts from the episodes at all. Given the choice between watching the show with an already-obtained Paramount+ account or having to go find the mid 2000s/early 2010s Blu-Rays that had the option to switch between original effects and the remaster and pay a premium to buy them, I think the extra cost isn't worth the minimal differences.