xaan,
We're here for you.
While we're not clear if this is an issue with one specific person's icon on a map or the entire People tab, we'd like to continue trying to help. Have you been able to use Find My Device or Find My Friends successfully in the past? We ask because, depending on your location, it may not be available to you. Check out this resource for more information: Share your location with your family In this resource you'll see that location sharing isn't supported in South Korea and might be unavailable in other regions due to local laws. It's possible that this may be the cause of your issue.
If you've confirmed that you're in a location that does have this feature, and the issue persists, you may want to Contact Apple Support to have them look into this further with you.
Take care!