I've seen House of Cards (starring Kevin Spacey & Robin Wright) where the first 5 seasons were excellent, but the sixth (final) season is shit. It's definitely been rushed during production on top of the drama with Spacey himself having to leave the show (due to allegations of sexual misconduct), so the show was rewritten into his character dying from a heart attack shifting the point of view into Robin Wright's character instead.

The ratings plummeted but the last episode is the worst reviewed via IMDb, like WTF was that ending all about?! They didn't even try to make it 13 episodes like the previous five seasons (cut it off at the 8th episode making that the 73rd and last, the season overall is just written poor and the script was composed last minute), too much was happening at once with no links to the previous seasons that made the series successful.