Why is there a Sim Card Symbol on left side of the Home Screen all of the sudden

Does it open the built-in weather app or did you install a 3rd party weather app?

Try a forced restart.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN)

Can you please provide a screenshot of what you are seeing so others may be able to help diagnose the problem?

That's a document symbol, not a SIM card. What happens when you tap on it, does it do anything? If not, it's probably in the wallpaper. What happens if you use a different wallpaper.

It’s a bug. It’s already been fixed with an update. Update to the current version of iOS.