Votre fichier fait bien 1920 x 1080, mais comme vous avez du le créer avec un téléphone tenu verticalement il apparait au format portrait (vertical) c’est en réalité un format de 1080 x 1920. Il aurait fallu tenir votre téléphone horizontalement pour pouvoir afficher l’image au format paysage. A ce stade, il vous faut réaliser votre projet avec un mode vidéo de 1080 x 1920
Your file is 1920 x 1080, but as you had to create it with a phone held vertically it appears in portrait format (vertical) it is actually a 1080 x 1920 format.
You would have had to hold your phone horizontally to display the image in landscape format.
At this point, you need to create your project with a video mode of 1080 x 1920
I used a video mode I usually use (portrait mode 1920x1080) applied a filter to the clip first, then applied the same filter to the timeline, then took off the one on the clip and ended up with this on the timeline filter:
Just to let you know, Shotcut already has two settings for 1080x1920 in Settings > Video Mode > Non-Broadcast. No need to create a custom video setting. They are called: Vertical HD 30fps and Vertical HD 60fps.