Screen recording on iPhone 16 looks blurry to people

Screen recording on my iPhone 16 pro looks good to me but when I put it in a video I edit on iMovie, after exporting it it looks blurry (and when I uploaded it to YouTube, it’s blurry on tge YouTube video). If it helps to say that I shot it vertical and put it into a vertical short. What do I have to tweak so people other than me can see it clearly?