So yknow how this mv p much shows the girls going back in time? I think this scene here represents them recreating the loonaverse(?).

So Heejin's vivid mv is described as the creation of the universe with a burst of color. This is represented by the intro which is all b&w but by the end of the video everything is filled out colorful and brighter than ever giving us the beginning of the universe.

But she's lost and alone in this new creation...

So pretty much after hi high and everyone finally gathers, butterfly and so what take place, and I'm too lazy to get into all that and I'm probably missing out a lot of info, but I think the girls solution to the infinite time loop is to just create another universe of their own.