Quality drops so hard they ruined an entire media

It's crazy to think back and remember 2015 (10 years ago, damn), when Seven Deadly Sins was the talk of the town. A lot of people were hyping it up and saying it was part of the new Big 3. The premise, the character's powers and the world's lore were pretty interesting at first. All my friends would only talk about it, and people would get a Netflix subscription just to watch it. But after the anime hit the Meliodas vs Escanor fight... it was like witnessing a trainwreck. Fans rebranded the series as Seven Deadly Frames (just like Record of Ragnarok and Blue Lock), and the disaster shed light on the anime's major problems (constantly breaking the power scale, the MC being the definition of Mary Sue and overall a weirdo, etc.). Nowadays there's movies and sequels in CGI here and there, but for the most part, it's like the series disappeared from the face of the earth and it only exists in our memories.

So yeah, what other media fumbled after a heavy quality drop?