Not to steal Alec's thunder here, but apparently some of these TV show re-releases are using single-layer DVDs instead of dual-layer DVDs like their original releases, meaning they have less storage space, and meaning they have to be encoded at lower bitrates, ultimately meaning that the video quality is reduced.

It sounds almost crazy today, but in the 2000s, DVD reviews were a big thing, and a part of the review was always video quality. Most people didn't pay too much attention to this, but there were occasionally movie and TV show releases that just weren't well-encoded, and were blasted for it. I know IGN did this and they mercifully still have most of their old reviews up, and some examples are The Matrix's glowing video quality review and Highlander: The Animated Series' terrible one. Nowadays, the baseline quality level is high enough it doesn't even come up in conversation, and I would bet most people who pop in a DVD in 2025 just go, "wow, DVDs really didn't look that good back then," even if the good DVDs of old used to look a good deal better.