Hatsune (v2.5.4)
The Hatsune release includes the Olek hard fork on mainnet, as well as several bug fixes and improvements.
More information about Olek hardfork can be found in Telescope (v2.5.3) release note.
The hardfork is scheduled to take place on the mainnet at block 24935500. If you are running a mainnet node or validator, please upgrade your node to this version before that block.