Avengers: Endgame (all the spoilers!)
I may add to this as I think of things, but it's nice to have someplace to dump thoughts, anyway. . . . . . . . . . . . For as much as Endgame messes with time travel , I think it does it pretty well and sensibly. That's not to say perfectly. Bruce's explanation, as well as the Ancient One's visual, sort of make clear they're going with the alternate/split timelines approach to avoid the butterfly effect. THEN they add the moral complexity of acknowledging these alternate timelines are valid as well, and shouldn't be screwed just for the benefit of their "prime timeline" (ie. the one we're following). That's why the make a deliberate effort to get the stones back to when they came from. That means there's a Loki that's alive, but he's in an alternate timeline. It also means that present-Thor screwed a parallel Thor by yoinking Mjolnir from that timeline (well, Cap could have returned that, though still kind of a dick