For the Original Series, the producers were just starting to explore color television and they used the whole pallette.
1990s Star Trek feels more "natural" to me: warm where you expect warmth (ship's crew quarters, hot planets), cool where you expect cool (Borg ship), fairly neutral otherwise, though some of the sets did have an office-park vibe to them.
Current Star Trek, specifically Discovery and Picard, are about as gray-blue and washed-out as ever.
The pictures in this tweet show it perfectly: https://twitter.com/ShelfNerds/status/1481452739754405889