Deleted app still showing up in mobile data page

my guess is that you never really deleted the app.. you likely just removed it from the Home Screen and it still resides in the App Library

review this

How to delete apps on your iPhone, iPad, and iPod touch - Apple Support

you can delete from the App Library by locating the app and tap/hold, select Delete App

or you can go to Settings > General > iPhone Storage > [app name] > Delete

If you are unable to delete, check:

Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Deleting Apps

make sure that's set to 'Allow'

so if you go to Settings > General > iPhone Storage, give it a bit to load.. Is the app listed there?

If you have a lot of apps..

You'll have to scour that list as they are listed by app size.

There is also a search function in the upper right.