Apple uses LZFSE compression for ipa packages. You'll need unzip with LZFSE support. For example https://github.com/sskaje/unzip-lzfse .

Exporting ipa packages in 2021

1. Go to the Mac App Store, search for Apple Configurator 2 and download and install it.

2. Connect your iPhone to your Mac, click on Apple Configurator 2, click on the top menu bar ->Account->Login, and enter your iPhone login Apple ID.

3. Click Action->Add->Apps... and select the app to download.(Before this step, you must have entered the details window of your iphone and make sure you have the app installed in your iPhone App Store.)

4. When the download is complete, a prompt will appear, do not click the button on the pop-up box at this time.

5. Open Finder, Use the shortcut command+shift+G and type the following path.

~/Library/Group Containers/K36BKF7T3D.group.com.apple.configurator/Library/Caches/Assets/TemporaryItems/MobileApps/

You can see the package we need, make sure to copy the installation package out at this time. This is the package we need to install.

6. Then change the .ipa file extension to .zip, and double-click to unzip it.

Yes i have opened plenty app by changing a .ipa to a .zip it does work then you have to find the payload folder then right click it and choose "Show Package Contents" then you are in the app