I watch maintenance and upkeep closely. I can't help it, it's in my nature. Here's my thoughts:
From the late 00's through 2015-ish, WDW ride maintenance was a joke. Things started picking up around 2015/2016 and I was actually pretty pleased for a while. Since re-opening after COVID, however, things are starting to look a bit sloppy again, and of course there's some laughably bad things like the cutouts on Gran Fiesta Tour.
I also maintain that, while WDW has had varying degrees of poor ride show quality for years now, their parks still look great. I believe that Universal is the opposite - the rides are generally in very good show quality, but the parks are quite worn and rundown. Some areas of UOR look so dingy and decrepit that I feel that "Six Flags" comparisons are apt, even if I don't agree with that comparison overall. If you want an easy comparison, just closely observe and compare the ground at WDW to Universal. At WDW - clean and polished every night, free of stains, cracks are usually repaired quickly by redoing that entire section. At Universal - the ground is always stained with grime or rust, faded, cracks everywhere, and if they're patched at all it's a very quick job that looks bad.