On Android, there are two ways to add a website to the home screen:
As a shortcut
As an app
When the website is added as a shortcut, the app icon is overlaid with a smaller Chrome icon in the bottom-left corner.
Solution 1: Add a valid manifest
To ensure your PWA is installable as a PWA and not just as a shortcut, you'll have to make sure your app has a valid app manifest. With tools like Progressier, it's done for you automatically.
Solution 2: Fix the Google Play Store app
If your app has a valid manifest, and yet your website is still installed as a shortcut, the problem is likely due to your Google Play Store app.
Why does it happen?
When a PWA is installed on Android device, the Play Store is in charge of generating an APK for your PWA. However, there are scenarios where the connection between Google Chrome and Google Play Store is severed locally, forcing the browser to fall back to the shortcut installation mode instead.
How to fix it:
Delete the PWA from your home screen
Open the Google Play Store app on your device
Make sure you're logged in to the Google Play Store app.
In the Google Play Store App, make sure Chrome is up to date. If not, update it.
Open the Google Chrome app and navigate to "Settings" in the menu. Make sure you're still logged in with your Google account.
Open the Settings app on your device and make sure it has enough storage space left
Restart your device
Reinstall the PWA