They changed their strategic direction for the show.
Go back and re-watch the first season, then try to watch the next two.
The first season is trying to compete with what HBO used to be known for: high-budget spectacles. It's like a blockbuster movie stretched out into a series. The lighting, the costumes the editing, the special effects, the casting, the writing, the sound design. It's comparable to Game of Thrones, Stranger Things, Band of Brothers, Wanda Vision, The Last of Us, Breaking Bad, the Walking Dead, the Mandalorian, American Horror Story, Westworld, etc. Of course, those shows aren't all perfect but they have high production values (or at least started that way) and were meant to be premium technical showcases. Back before the days of streaming, this was the quality of show where you'd have to pay your cable company extra to get that channel.
Immediately with season 2 of the Witcher, everything feels worse. The most obvious to me is how Yennifer went from her ridiculous outfits to dresses that look like they're on sale at Kohl's today. The lighting, the makeup, everything. It's the quality of basic daytime cable TV, the kind that is still broadcast over the air for free.