Well on the same site ethernodes.org, the majority of Ethereum nodes are running on AWS at 45% [0]. Due to this announcement from AWS [1], it is going to become even more centralized.
So the claim of 'extremely decentralized network' is somewhat of a myth and a falsehood.
Ethernodes is known to be inaccurate [0] and is missing a lot of nodes because they can't index nodes that are maxed out on peers or are behind NAT and can't accept incoming connections from nodes they haven't connected to first. I know this for a fact because my own personal node (been online for over a year now) is not indexed on ethernodes, nor are 70% of the peers my node has. Only 2 out of my 15 peers are AWS IP addresses.
As a general rule - its very difficult to get anything close to an authoritative census of a decentralized peer to peer protocol.
Correction: according to your link, only 28% of Eth nodes are running on AWS (1579 of 5632 - click "Network Types").
However, many of these are not mining nodes that secure the network (and therefore security of the blockchain), but instead are nodes run by dApp/web3 developers to handle things like indexing NFTs and the current state inside a smart contract.[1] It is easy to spin up a geth node for a task like this—and by default mining is not enabled. I haven't seen any stats on the total number of mining nodes and their network types.
I agree that too much of the traffic is going through AWS, and I suspect all of these stats will need to be re-examined after the PoS Merge.
You can choose one of ~20 different free RPC endpoints: https://ethereumnodes.com/
This doesn't include private or paid RPCs or just running your own.