Speaking for myself here:

• Shorts loop automatically, something I find annoying
• Shorts have loads of UI over the video by default; while there is a “clear screen” button in the context menu, it doesn’t persist, and is extra interaction that a normal video doesn’t require
• It’s easier to scrub through a normal video on mobile; while there is a progress bar at the bottom of a short, you can’t drag up on that bar to get fine-grained seeking

This is my “old man tells at cloud” moment and I’m okay with that.