Vitalik Buterin, the co-founder of Ethereum (ETH), has ignited a debate about the classification of various layer 2 scaling solutions. The crypto veteran has claimed that Ethereum’s validiums should not be considered genuine rollup solutions. The statement came in response to a post by Daniel Wang, the founder of Taiko, an Ethereum rollup solution, who said if an Ethereum rollup relies on an external data chain, such as Celestia’s modular blockchain, then it should be classified as a validium. “This is correct.