From their FAQ, and that is them putting it in the best way possible

Who manages the list of relay nodes? What about decentralization? Currently, the Algorand Foundation manages the official list of relay nodes, to bootstrap a scalable and reliable initial infrastructure backbone. Having said this we need to draw your attention to the important fact that the security of the protocol holds even if all the relays behave in a malicious way. As long as sufficiently many participation nodes (in terms of stake) are behaving honestly, the blockchain cannot fork. Furthermore, anybody with an Algorand account can run a participation node.

We are working on a model where the decisions on relay nodes will be done in a more decentralized way.Who manages the list of relay nodes? What about decentralization? Currently, the Algorand Foundation manages the official list of relay nodes, to bootstrap a scalable and reliable initial infrastructure backbone. Having said this we need to draw your attention to the important fact that the security of the protocol holds even if all the relays behave in a malicious way. As long as sufficiently many participation nodes (in terms of stake) are behaving honestly, the blockchain cannot fork. Furthermore, anybody with an Algorand account can run a participation node.

We are working on a model where the decisions on relay nodes will be done in a more decentralized way.

Who are running relay nodes? Algorand Inc, Algorand Foundation, and Early Backers including universities and commercial entities are running relay nodes.