My video is not the correct size coming from iPhone

Am I doing something wrong to have the video so small? I filmed directly from my iPhone, used iMovie to edit the length and then uploaded to TikTok, but while it's uploading, I noticed the video is really small. What happened?

https://preview.redd.it/3bodchpco4ne1.png?width=268&format=png&auto=webp&s=6a305bcecba67cc4f1486bec969b7d3b683730f2