There were already cracks by season 4. I think it's pretty evident that D&D's end goal was the Red Wedding and they didn't have particularly much interest after that.
House of the Dragons isn't much better.
Knight of the Seven Kingdoms managed to be worthwhile just because it managed to avoid the attention of all the usual suspects and got to have its own identity, I actually decided I should give the show a chance just because of how different this piece of music was
https://youtube.com/watch?v=pxXAzdZSlFI