No, there are no instances, there are just caching servers called "relays" that are run by many different people. You create the content on your device and the

No, there are no instances, there are just caching servers called "relays" that are run by many different people. You create the content on your device and then send it to many of these relays (usually 10-20) and other users pull the content from also 10-20 relays. So if one relay decides to block you, then people still get your content from other relays. If all relays decide to block you, then you can (quite easily) run your own relay and tell your friends to pull the data from it. You own your data and you can resend it to wherever you want (it's signed by your private key, so it's verifiably from you).