After updating core to 8.7, the input fields for shipping and billing information are now hidden and Edit buttons are in their place. This has allowed users to checkout without entering shipping and billing information. How can I show the required fields by default and get rid of the Edit button?
It looks like you have Commerce AutoSKU installed. The authors of the module modify one of Drupal's validation constraints which checks if fields are empty or not. This causes the addressbook form element to break, which what you're seeing, on top of other problems.
The issue is reported here, https://www.drupal.org/project/commerce_autosku/issues/3086828
The solution is to either uninstall the commerce_autosku module or apply the patch in comment #3: https://www.drupal.org/files/issues/2019-10-18/3086828-3.patch