Seeking solutions for retaining old discontinued apps that no longer accessible due to recent iOS updates

If you are experiencing any difficulty with third-party apps then please contact the app developer directly --> How to contact an app developer - Apple Support

If there is a new and updated app, again, reach out to the app developer directly and they should be able to guide you with that. Apple doesn't have any control over 3rd party apps, nor the data contained in the apps.

Contacting the developer is no longer possible, as the app can’t be opened and it has been withdrawn from the app store. I don’t have an email for the developer or even the name of the developer. Consequently, a year of my journal, 2020, that I failed to back up is no longer available to me. I should be able to at least convert the data in it to a text file or as an import to something else! Of course I should have backed that up, but 2020 was a very strange year in many ways. I’m very disappointed I can no longer trust the Apple App Store as a source of journal apps.

Apps that don’t get updates eventually fail, and apps from any developer (including Apple) can be abandoned.

Acquire a stuck-on-an-older-version iPhone or iPad, associate it with your Apple ID, load the old app there, and transfer your data.

It might also be possible to extract the data from an app backup, though that amounts to reverse-engineering the app and its storage. If the app stored that data securely, that might be a problem. If the data was stored in an unencrypted file or unencrypted database, less so, but still a hassle.

Ok, so I tried that and got no response. All my data is backed up to the cloud. I bought the new, updated app but can't find a way to transfer the data. Any ideas?