Is there a fan edit that fixes the last season?

No and it's not really possible. We'd have to have so much much alternative footage to edit together, which we don't.

There is no fixing the last season.

That aside, I always thought if they had taken the beginning of the last episode, spliced that into the ending of the previous episode, and after Dany's speech about conquering the world had a cutaway to Snow and Tyrion with their reactions, that would have been a greet cliffhanger going into another season.

I understand that I am not answering your question about a fix for the season, nothing would save season 8, it was horrid.

To fix it you need the final book of the series "The Winds of Winter", which is not finished as yet, has an rumored publication date of November 2023.

The final season showed how useless the script writers were without the book.

To be honest, Season 7 was shit as well.

People are dead on. You really can't fix it. There are some great ideas out there on where they should have gone, but largely it's not JUST a writing problem.

The writing is awful and it is a problem, but if you like seasons 6 and 7 then it probably won't be the writing that would have ruined it all for you.

There was a major problem with story plot payoff, that couldn't have been done properly in the time frame delivered. They attempted to do a check box scenario that lead to horribly cheesy and predictable outcomes just to try to give some resolution. You can't have 7 seasons of build up and end the major threat in a single episode... No amount of writing would have made this not seem awful.

Season 1 through 5 they had created the "rules" of the world, and season 6 through 8 seemed to almost go out of its way to breakdown those same rules.

As an example: travel in Westeros was difficult time consuming and dangerous. Seasons 6 through 8 stopped carring about that detail and travel become nothing but a single bit of dialog in the story.

The entire story is based on the "fog of war" meaning main characters could be within a stones throw, and they might never know each other was there. 6 through 8 is full of last second saves and heroic entrances that would make any 80's action movie blush.

The writing CAN be blamed for many of the beloved characters becoming boring plot devices. Tyrion, Little Finger, and Varys are the most obvious of these problems. The writers had no idea how to write these characters without the books.
Again this started happening in season 6 though.

I think you can squarely put character's complete heel turn to their charcter arcs in the last season on the writers as well. Jamie and Danerys are key examples of this. I think Danery's story was decided season's ago, but they waited too long to show the signs, so it came off as cheap and ineffective.

I agree with everyone else, fan edits can't fix that mess. There just isn't enough good material to work with, fan edits are only good for fixing overblown messes that desperately needed editing before they were released, like the disastrous "The Hobbit" films. No, to fix the disaster that was S8 of "GoT" someone would actually have to go back and shoot at least two seasons, beginning where the real S8 started.

I have an outline, if anyone in Hollywood would like to pay me money for it. I work cheap, by Hollywood standards!

The final season plot wasn't that bad, really. I heard that Martin approved the broad outlines.
They just didn't do a good job of connecting the dots, filling in the motivations and the changes of heart with plausible explanatory scenes. Mainly because it was too rushed. What was the hurry?