Apple added a new feature that helps prevent users from purchasing accidental subscriptions to apps. Now there is an extra confirmation step.
The feature was found by David Barnard, who tweeted about his discovery:
After you confirm a subscription with Touch ID/Face ID, a window will popup asking if you really meant to do that. You can either tap Cancel or Ok to continue. This goes a long way to prevent unscrupulous developers trying to trick people into subscriptions.