Fix your grip first : you are clenching your first, almost panhandle way, instead of having a correct V grip. Because of your grip and your tense arm, the racket is perpendicular to your forearm, not allowing you to use your shoulder/elbow correctly (otherwise the racket face will slice the shuttle) Also because of that, you are consciously forcing the pronation and you wrist is bending in too. So fix the grip, relax, try to squeeze the handle instead of forcing the pronation. Post a video of you swinging without a shuttle so that we can correct it little by little
The video quality is not so good, but I think that the girl at the right is Isabel Herttrich (now Isabel Lohau), I believe that the girl at the left should be national level too. So, the shot quality should be okay. The video is from one of ex-german national trainers. This is Isabel Herttrich winning the Denmark Open 2020 together with Mark Lamsfuß:
