Amazon Doug DVD set picture quality

I recently noticed that on the DVD sets (especially for season 1), there's a lot of color shifting and some occasional picture shaking. I've heard a couple of people allege that that's how the show always was, in its original airings, but I find that very difficult to believe.

For one, these people are essentially saying that, despite the fact that these DVDs were made from masters tapes that were about 17 years old at the time of production, they didn't in any way age between then and now.

Additionally, in certain episodes, I can freeze the picture and see blue spots or other assorted junk that looks like classic signs of an aged videotape.

I may have been too young at the time to have formed vivid enough memories to remember for sure exactly what it looked like on TV back in the day, but I'm pretty sure the original airings and first couple years of reruns looked sharper than that. Heck, there are Youtube clips of old commercials for Doug that people uploaded from their VHS recordings from back in the 90s, and the picture quality from those clips looks steadier and more consistent color-wise than what's on many of the episodes on the DVD set.

Anyone have any thoughts on this? As far as I know, aside from tape degradation, there's absolutely no other reason for the background colors to be changing every 3-5 frames or so.