Promised Neverland, though I only watched the first season due to how much they changed for the worse in season 2. I've read most of the manga so I knew what was supposed to happen, but I've never got around to finishing it.

Anything where the older role model ends up dating the child they just spent the whole start of the series essentially raising. It has happened twice now, and I'm repulsed every time q.q why is this even an issue??

Controversial, but Attack on Titan.

When they realised how much money they could squeeze out of the IP, they decided to stretch the story way to long. It should have ended already.

Ousama Ranking recently comes to mind. Such a bizarre and wonderful setting filled with intrigue and all I can remember about it by the end was the made the MC op and the other prince wants to marry his father's childhood sweetheart and villain, after she basically killed him

Interesting responses here, lots of weird stuff! The most recent I've seen went a bit different - Super Cub, a slow-burning SOL that seemed to be headed to a relatively exciting and satisfying conclusion. But it just turns out to be full of plot holes and queer-baiting at the end.

Charlotte rushed the ending and fumbled it bad.

Wonder Egg Priority. No, WEgg, commit die is not caused by a jealous android and her weird program friends.

I'm not sure if Guilty Crown fumbled the ending or if it just was garbage right from the outset, but I distinctly remember everyone hating its big tone shift with the MC going hyper edgelord mode.

This is probably far from the "worst" example, but the most prominent and notable example for me is anything from the FATE series--Stay Night, Apocrypha, Zero... Really, pick any of them. I don't know if they're "bad," but the drop in writing between the first half and the last half (and last handful of episodes particularly) is so consistent across the series that I just go into any FATE show expecting that it's going to fall off to varying degrees by the end.

I imagine almost anything with a Gecko Ending fits. Also here should be the series where something happens and they're rushed to finish it in the next 2-3 episodes instead of 10-15 as planned or something on those lines, faintly recall seeing a few like this before. But both of these are special cases, more interesting is when there's no external pressures and there's plenty of material, yet they screw it anyway. Rosario to Vampire comes to mind, the manga had the usual harem and comedy shenanigans, but went full shonen. The anime discarded most if not all of the shonen for the harem/comedy shenanigans and ended funny but less good as a result. Never watched S2 because of this, no idea if there's more. I suspect nearly every case in the thread is behind the scenes a result of executive meddling, but that's just gut feeling.

I don't watch a lot of anime, but how about the original Evangellion? My understanding is that the last few episodes were deeply confusing and disliked when they came out, to the point that the movies were created partly to "fix" the ending.

So for me it would have to be the original Dragon Ball tv show. I fell in love with the show around the Tien Saga for how meticulously animated the fighting was. Every punch and kick was seen and the focus was on martial arts. This continued through the King Piccolo saga, which I also loved.

However, I was massively disappointed with the Piccolo Jr saga. To me, it seems like the show switched from being focused on martial arts to generic energy blasts and poorly animated “flurry of blows” that really watered down the quality of the fights. Where before we had well drawn punches and kicks now we had people yelling loudly while blasting energy beams.

I’ll die on the hill that this was a “jumping the shark” for the Dragon Ball franchise that it never fully recovered from. Future DBZ seasons were a bit more creative (thinking of Goku holding Raditz while Piccolo blasted him) but the show as whole never really returned to being about “martial arts” the way it was before.

I feel like an old man shaking my fist at a cloud though, as I’ve yet to meet one single person who misses that focus/aspect of the old show.

Since the worst examples I can think of have already been mentioned, I'll just throw in that Boku No Hero Academia is making me pretty sad these days. It's like they decided to stretch out a few things that were shorter in the manga for a reason and it's gone on for so long that it doesn't feel like the same story at all anymore. I miss what the show used to be.

ETA: Ascendance of a Bookworm was really fun right up until she decides to dump everything in the trash and join the church.

Erased and To Your Eternity both fell off so hard, I'm not sure which upset me more. I don't want to spoil for anyone, but man.

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

The last season of Food Wars felt really rushed, like a shell of the former seasons. Absolutely everything felt unnecessarily shortened.

This isn't like awful, but it's noticeable. Full Metal Alchemist (brotherhood? I forget who came first) we started great and strong, good pacing, but then they ran out of source material too quickly. SO, they started making it up as they went. I stopped when the general planning a coupe flips to a genocidal maniac, the character shift was so jarring. Apparently further down this path they lose their alchemist abilities and get shot to WWII to fight some Nazis. It was so off the rails, when the manga started up again they completely redid the anime from the beginning. I love this anime, but I have to make a guide on how to watch it every time I suggest it. The second attempt didn't do as well with the early episodes like the first one did, probably because they were trying to catch up. Wild ride, still worth it.

I feel like 90% of anime starts with an interesting idea but couldn't continue for long. The ones that doesn't fumble are the exceptions.

Surprised nobody mentioned Tokyo Ghoul, it's probably one of the most legendary fuckups in anime history.

Also the second season of The Promised Neverland.