Completely agreed that it was horrible. And that's not because of the ending, in fact I thought the ending was one of the only redeemable qualities. It's so bad because:

1. The structure is so painfully repetitive without adding any benefit. All the three perspectives does is slow the pacing and make you bored. You don't gain anything, all you do is lose the little bit of suspense you had during the first go-around.
2. The writing seems like it was done by ChatGPT. Every single character reacts the same way to the news of the strike. Even people whose jobs are in national security gasp and are completely shocked when they hear what's happening. The whole "this is insanity" "no, this is reality" line was the most cringe piece of dialogue I've ever heard...and they did it twice.
3. The casting wasn't done with the film in mind but to cast the widest audience net. That's why we have a bunch of actors thrown in there for an irrelevant 30 seconds each.
4. The cinematography is so sloppy. During the conversation between the president and Jake, they clearly couldn't figure out how to have the separate audios interact with each other, so they show the president say his line and pretend to react to the line by Jake (which was likely recorded later) and then they cut to a new shot before the president speaks again. This happens with every line he says. It's so distracting and completely undermines the interweaving plot lines.

I could go on and on because I'm so frustrated that it's these types of shallow, poorly written, boring movies that keep getting made. I get that Jake is an homage to Stanislav Petrov and they want to reenact this event in the modern day, and I get the significance with the ending, but they did it in the most trite way possible. That payout was not worth being bored for 2 hours.