Take Game of Thrones. The first few seasons (I’d say 4) are truly phenomenal. The next 2 are still good. The remaining 2 seasons ruined it so much that I’ll never revisit the first 4 (or 6) seasons, because the conclusion is so fucked up and lazy that it’s not worth it.
That’s how you change the quality of another movie (or season) - by taking a huge shit on its legacy.