Re: iMazing. It's no longer a great option to do this as they too pull from the App Store and not backup the actual app(s) from the device.
imazing.com
That link is from 2017, so oooold, so probably don't have copies of old apps on PC/Mac to manage via iMazing.
So need to do some initial planning if want to have apps available for restore: will need to do an initial app update within iMazing to get a copy of the version you have/want that you can use down the road. And if no longer in App Store, out of luck.