General requirements for all apps, number 4, letter C:
Your app must be a stable, finished product when you submit it to the Shopify App Store. It shouldn't be in beta or an otherwise unfinished state. If your app is broken or has bugs, then it can discourage merchants from using it, and in some cases it might even interfere with their businesses.
This app literally have "BETA" in the title... https://apps.shopify.com/checkout-transparente ( and it is a checkout app! )
So why they approved?