Currently the open sourced cloud function provided by Firebase/Stripe uses onwrite to Firebase database to trigger the charge to Stripe:
It seems that it would be more direct and faster to just call Stripe using https trigger instead of writing to Firebase local database which syncs/writes to Firebase server database, which then triggers the cloud function call to Stripe.
Will there be any problems using Https call to trigger Stripe call? What advantages are there for using onwrite trigger instead of https?