Although TV as a medium is meant to blend novelty with consistency, it's inevitable that a TV show will change over time as writers think of new storylines to explore and actors get more comfortable with their characters. Though many shows will completely change for the final season, sometimes, a show will change much earlier.
Not every show can find its niche in season one. The earliest installments of a show are often unusual in retrospect, before the creators completely figured out the structure and goals of the show. As a result, many of the most popular shows have drastic shifts in camera, style, genre, character, or tone after their first seasons.