I really like the visual style of this poster!

I do have some suggestions on some things that might improve it:

• Try to minimise text and maybe use bullet points
• Explain “federated social networks” instead of decentralisation. Decentralisation has many meanings but the meaning of “federated social network” is more specific
• Emphasise that anyone can host an instance for their friends/community
• Because anyone can host an instance and become part of the network, the people who actually contribute to and run communities have more power and control (you could also say it takes control from corporations and gives it to the communities themselves)

I think what you have now is really good and informative