Something I noticed back in the VHS days is that the sound of season 4 episodes like “Long Live the Queen” sound echo-y or something compared to other seasons. It carried through to the DVDs. What went on?

IMO: Bad mastering. It's also sort-of proof they used the syndication videotape masters for the DVD set, at least for that season.

In some later seasons they used the actual network masters because you see original bumpers and Liz intros.