For me, writing a climax is usually easier than following it with an effective denouement.
When I begin imagining a story, I can usually produce a scene where the intensity of the conflict comes to a head. In fact, it often happens that I’ve thought about several alternative climaxes.
My challenge is the unknotting of the story elements that follow the climax. When it goes well, the story has a satisfying wholeness. Unfortunately, the most obvious or easiest conclusion is not the most satisfying. And so, I edit, I discard and reconsider, I try different possibilities like trying on jewelry until the look is right for the ensemble.
I like an ambiguous denouement, especially in flash fiction. I don’t believe that readers have to see all questions resolved with certainty. But even an ambiguous conclusion requires careful unraveling of the story knots.