How I would fix the final hours of Game of Thrones:
Have Dany come in, full army and boats and shit in tow. No foreshadowing that she's the mad queen blah bluh bleh. She's gonna siege the shit out of king's landing. It's gonna rock. Euron's armada is nowhere to be seen.
Then Cersei asks to parley. Dany buys it and goes in with her honor guard. This is a trap because of course it's a trap. Part of the Golden Company plus the Scorpions in the city walls attack Dany's guard and kill Missandei and one of the dragons, the rest of the Golden Company ambushes the Dothraki / Unsullied land army, Euron's ships come from a inlet or fjord or whatever and block the bay.
This has to all happen in one blow to establish Cersei, again, as the Queen Bitch of Westeros.
Because what needs to happen next is Dany immediately getting on her last dragon and torching anything that even looks like a threat in a spiral centering on the Red Keep, while Grey Worm does the same on land - he's absolutely pissed as well - while the Dothraki just do what Dothraki do.
What has to happen here is that the audience needs to buy it. It should make perfect sense that, yes, everyone is sick of Cersei's shit. And her death needs to be, like, something that makes everyone stand up and applause. If we take Arya off the Night King nonsense we can even have her "voice in the shadows" batman style hounding cersei through the keep while Clegane kills Clegane.
After that you go back and pan over the city and now you can let everyone realize that jesus christ what have you done dany.