If you find that an app is no longer working properly you can easily delete it from the device and then reinstall it again for no extra charge.
After deleting an app, open the App Store, tap your Apple ID profile picture (in the top right of the screen), and select Purchased. If you have iCloud Family Sharing enabled, your family will appear on the next screen. Here, tap My Purchases and select Not on this iPhone. This will show all the apps you’ve previously downloaded, but don’t currently have on the device.
Tap the cloud icon to download the app again for free.