Have you ever noticed how the Papal flag with its triple crown, draped stole, and crossed keys, is the same basic design as the Jolly Roger flag with its skull, mandible, and crossed bones? Historically, which flag copied which flag? The Papal flag is a unique design among today’s national flags.
The keys are on the Vatican flag, but the idea that earth binds heaven may be a mistranslation.
In the ‘Our Father,’ it is ‘on earth as it is in heaven’ (the reverse).
The NIV footnote has for Matthew 16:19, “Whatever you bind on earth will have been bound in heaven.” So heaven affects earth, not earth binding heaven. Similar footnote for Matthew 18:18.
So the Vatican may need to redesign its flag.
Possibly “heaven” meaning expanse, is inner consciousness, and that sets the stage for how we view “earth,” the material world we inhabit?? So the “key” is that your inner consciousness is very important.
Jesus obviously knew nothing of a pope or a Vatican flag.