App no longer functional on iPhone 11 after upgrade
When I upgraded my iPhone 11 to IOS 15.5, an important app was no longer functional because the developer had not updated it. That app has a bunch of data important to me and I need to retrieve it. Is there any way to reinstall the previous IOS temporarily or any other solution to being able to open this app and retrieve my data? Thank you.
iPhone 11, iOS 15