It's not. Their own people say it over and over and everywhere that they cannot decentralize the "relay" because the entire architecture assumes a single source of truth for all the data, all they can do is hope people will migrate to an alternative server in case the canonical one becomes malicious. PDSes are useless and meaningless because no one talks to them except the "relay".

They also cannot decentralize the identity system. Again, they say it themselves, and their plan is to give control over it to a more neutral party -- which you can say it's a good idea or not, but it's not decentralization.