I didn't find season 4 that bad though, but yes it's a common occurrence these days.
It's a bad writers syndrome, at some point writers are out of ideas or didn't plan to run for that long and it reflects in the writing...
Quantity over quality has literally killed the art of TV making, I fucking hate Netflix for it, they started this whole quantity over quality business model and everybody is following them, leading to extremely low standards and the very rare decent release.
People were saying that we were in the golden age of TV a couple years ago, well, I believe that ended around 2016-2017 maybe.
Sorry for being so pissed about this, wrong topic for it too, but I have always loved TV shows and it hurts.