I think this film would have been better if it focused on the "science" rather than people breaking into a bunker. Like she sees the plant growing so clearly the earth is healing but it's never mentioned again? I don't think we even know WHY the oxygen is gone in the first place? Not great world building. The better premise was that film about running out of oxygen and time travelling to fix it.
Though it would have been a better plot twist if they got to Philly and everyone was dead.
I think this premise might have worked better as a series where they had to work together to survive, rather than the classic "we are gonna kill you and take your stuff cause humans suck".
Overall if you wanna watch a simple easy dystopian and you like a b grade movie it's not the worst.