Lost and GoT.
both went from amazing to terrible because of the conclusion.
Thought Lost's ending was fine. Far from the perfect ending, and the show definitely peaked earlier than it's end, but it managed to have a very satisfying conclusion for most of its characters, with some hard hitting emotional scenes packed in the finale. The mythology stuff was, as expected, pretty surface level in the end - "its magic, fuck you", basically. I feel that people were absolutely fooling themselves into thinking that it'd be anything more than that after the Jacob reveal episode in S3, which basically straight up was pure fantasy. And that was followed by S4 introducing Miles who could talk to ghosts, a mechanism that can move the island... and if THAT weren't enough, S5 had the ancient egyptian "cradle" of the smoke monster, the reveal that it took John's place, the whole Jacob "touching" people angle. So yeah, by the time S6 was on, I was honestly shocked that there were people still expecting some big genius reveal that makes everything click. But at least characters stayed true to themselves to the end. At least Lindelof learned his lesson with The Leftovers, which is very similiar to Lost excpet it doesn't at any point lead the viewer to believe that the mystery would be explained.
Sadly I fully agree on GoT however. The white walker storyline got utterly simplified and made meaningless - the so called "long night" barely lasted a single night, all it took was one single battle to defeat the greatest threat of the whole show, and it didn't even include Cersei's army. Which is really the icing on the fucking cake. I went back to rewatch some of the early seasons recently and the way white walkers are slowly built up throughout the episodes just feels so fucking pointless and laughable now. Before S8, it was some of the most exciting stuff in the show. Even just getting a glance at the Night King was amazing. Hardhome's last 20 minute showed the white walkers as a considerably more menacing and serious threat than the fucking Long Night. But all that, I could've forgiven if at the very least characters had satisfying conclusions. As fucking if. I don't even mind Dany going mad, but doing it 2 episodes before the end just made it feel utterly rushed and pointless. It was so obvious what was gonna happen to her. Jon ended up being the biggest fucking loser in Westeros, his entire story was building up to go against the Night King, but subverting expectations was more important than logical, satisfying character arcs for D&D. But at least he could be king, right? Lmao, no. But how about this fucking guy who the writers couldn't do anything with since S5? Bran becoming king was possibly the most outrageous thing that could've happened. The janky "Why do you think I came all this way" justification at the end was truly the icing on the cake. It makes zero fucking sense. There is nothing to indicate at any point that Bran cared to become king, or that he would be a good ruler. Cersei staying alive past S7 was curious, I thought, maybe she has some good shit in S8. Well, she had fuck all really. In fact, the only reason why she was left alive, I feel, was so that Jaime can undo 7 seasons of character development and die like an idiot. Again, giving Jaime redemption and allowing him to seperate himself from Cersei once and for all might have been the "predictable" thing - and for some reason, D&D decided that predictable automatically means bad, so they once again subverted everyones expectations and just character assassinated him.
The funny thing is that if you just imagine an S8 where all the "predictable" things happen: Jon ultimately delivers the killing blow on the Night King, Jaime or Arya kills Cersei and Daenerys becomes queen, then I think the season would've been received far better. Because at the very fucking least it doesn't undo 7 seasons of build up.