Staking distribution

Hi people

I read that several community stakeholders raised concerns about the centralization of the network post-merge.
I quote decrypt.co back in october 2022: "As of last month, 13.5 million ETH (worth $22.3 billion at the time) had been staked on the Ethereum network, with more than 60% of that ETH sitting with Lido Finance, Coinbase, Kraken, and Binance."

Since I am writing my master dissertation to major in Business Engineering, I want to include the evolution of these centralization concerns and analyse the staking distribution over all parties. I found the following graph on beaconcha.in/pools

Staking distribution

To take away from this graph we can see that the 60% of staked ETH sitting at 4 parties is definitely not the case anymore. Can anyone confirm if this is a correct graph? Or can I find a more detailed graph somewhere else? Could some of the validators of the "Unknown" category be related to a big exchange or liquid staking protocol?

Enlighten me if you know more about this issue, thanks! :)