I have also had this issue. I would recommend giving it some time. This issue especially gets worse when there is less than a few GBs of storage left on the iPhone. I have tried opening and closing the app, going back and forth in the Settings app pages, and at some point the numbers have refreshed. The key is just put the phone down for a sec and let it search for storage differences.
Tip: with photos, you need to delete them from recently deleted as well otherwise photos's storage number won't change.
Tip #2: on iOS 14, it is common to 'remove from Home Screen' instead of 'delete app'. Just want to make sure you are on the right path... let me know if this helps.