Why is the health level so low? Is Ethereum not decentralized?

This is a misconception. Ethereum is extremely decentralized but holds itself to the highest of standards. To put it another way, Ethereum’s “low health” is what other chains would consider an extraordinary achievement.

For example, while most chains just have one client (typically forked from Ethereum), Ethereum has more than 6 consensus clients and 5 execution clients.

This is great, but we still don’t consider this ideal and strive to have an even distribution among clients (as opposed to 55% Prysm usage, which would result in a Consensus Client Diversity score of 45%).