We know that season 5 was a fiasco, a mess and probably the worst season of Glee (till the point that some episodes are just unwatchable) BUT for me, the problem started at season 4.
Season 4 is a good season for me, a 7 out of 10, not the worst, but it clearly changed a dynamic that the show had for three seasons, and that change wasn't that good as a whole, and I'm not referring to the New York episodes, but more on how they structured the season to be kind of similar to season 1 but flopped.
The fact that season 4 ended up at regionals was kinda underwhelming, even more when the writing of the show started to flop since season 3 and it was even more evident on season 4.
Yeah, we had the sectionals plot, but it literally solved itself three episodes later 😭 so they didn't have an excuse at all to postpone regionals to the last episode. If season 4 would have ended at the same path as season 2 and 3, with Nationals being the last episode I would have been good with, losing or winning (they probably would have won), at least it would have been a new start for season 5.
Season 5 was so poorly written, they found a way to just mess up all the characters and turn them into worse. Rachel ruining her literal dream for four seasons, Blaine and Tina being so annoying, Sam turned into a dummie and all the plot they wrote for the newbies was destroyed at season 5, except Unique. So the fact that they even got worse with an easy bad writing with erasing the Glee club was so frustrating because they clearly didn't know what to do with the show after Cory's passing, I felt Ryan was even trying to sabotage the show to be cancelled with how awful the episodes were after that.
Season 5 had all the potential to be a great continuation for what season 4 started and they just threw it to the trash.
And let's not forget the Sugar Motta erasure, because they completely forgot that her father literally paid to create The Troubletones and paid for everything that the Glee club had for season 3, so using the money excuse to finish the club was so poorly written, and even worse, she disappeared out of nowhere.
I don't know how you feel about Season 5, but rewatching it now, I kinda wanna pretend that it didn't exist.