[polezo]

Those are staking pools, which represent thousands of individual users, and the largest one (LIDO) also has has additional decentralization that is not well captured by looking at just reward address. The reward address is a contract that individual users will be able to tap into.

Worth adding it's also not substantially less decentralized than PoW mining was, the status quo was 41% of hash power controlled by 2 pools. At least now it's using significantly less power and is largely more non-custodial.