iPad’s Notability app
I bought Notability app in my old Apple ID in my iPad and now i am use to new Apple ID in my iPad but Notability disappeared suddenly.
iPad, iPadOS 14
You can purchase the app using your new Apple ID or you can try setting up Family Sharing between the IDs if you want to be able to share purchases made with the IDs.
By changing Apple IDs, you may have lost all access to the data that you had in the app.