Yes, the fight felt too long, clearly the mangaka was told he only had 26 chapters to round up the story and decided to make a fight much longer than it needed to be to fill pages instead of going forward with the plot, so it would end in the climax after the battle, I gues with a resoultion epilogue of the MC looking to the future and how he will have to make so bad shit not in the original history happen.
It made me remember Pumpkin Scissors anime from Gonzo when the last episodes had a stupid fight with 2 assassins lasting multiple episodes when the resto of the thing had the main team putting down elite soldiers and tanks in a couple scenes, and it felt dragged out the whole damn time.