"The Ethereum (ETH) Dencun upgrade will be active on the Holesky testnet within 12 hours," reported EtherHub co-founder 'sassal.eth' (account X). The ETH Foundation previously performed the Denkun hard fork upgrade on the Goli and Sepolia testnets on January 17-31. The mainnet upgrade is expected to take place in early to mid-March.
Blockchains always upgrade to address scalability issues they face. Ethereum is no different, and this hard fork is a rollup to improve it. Ethereum's Dencun hard fork is a massive upgrade that includes a number of updates, including EIP-4844 (proto-danksharding) to improve ETH scalability, system optimizations and network security improvements. This is expected to result in a more than 10x reduction in fees.