Solana has recently expelled multiple validators from its delegation program due to their involvement in sandwich attacks targeting retail users. These attacks, known as Maximal Extractable Value (MEV) attacks, involve altering transaction sequences to gain more favorable prices, ultimately harming retail traders. The Solana Foundation has taken decisive steps against validators who modified their systems to carry out these attacks, resulting in the expulsion of several operators from the delegation program for violating best practices.

The Foundation typically supports validators by delegating SOL tokens to them, allowing them to operate without owning a significant amount of tokens. However, this support is conditional on the validators' performance, ensuring that only reliable validators receive rewards.

Mert Mumtaz, a co-founder of Helius, a Solana RPC provider, mentioned that expelled validators can still function on the network but will not receive the usual benefits. This decision sparked discussions on Solana's centralization, with some community members arguing that the blockchain is more centralized than it appears.

The action taken by the Foundation reflects its commitment to fairness and protection against potential threats. Noteworthy is the fact that Solana validators have earned more from MEV than those on Ethereum.

In addition, the revenue from MEV on Solana has seen a significant and rapid surge since mid-March, reaching unprecedented levels. This increase in revenue underscores the challenge of balancing incentives for validators with safeguarding retail users.