There's a lot of silliness in GEN, but let's focus on the OP's point.
Yes, I was quite annoyed about the reuse of the exploding BoP for two reasons. At the time, I knew it was from TUC because, well, TUC had been the last Trek movie I saw before this one, so it was still fresh in my mind, so to speak.
But what really
annoyed me later was when I found out that originally, the Duras sisters were supposed to have a newer, larger and better ship, one more equal to the Enterprise, so that it made more sense when it destroyed the latter, as opposed to a dinky BoP that destroyed the Enterprise thanks to a lucky shot.
But because someone wanted to reuse the exploding BoP footage to save a couple bucks, TPTB decided to nix the building of a new Klingon ship model and reuse the old BoP in order to match the ship with the stock footage.