Deleted old app , iphone storage shows in system data the circle spinning around for over 15 mins. is this normal ?

Haiyaaa! From what you provided it seems as when you try to view how much storage "System Data" has used it is not loading, therefor you can not see how much storage it has used. If this is happening please try to restart your iPhone, learn how here: Restart your iPhone - Apple Support

Best of luck resolving your issue!

it might not be loading correctly im not sure whats going pn