The Neo release includes the Miko hard fork on mainnet. This release implements REP-0007: Implement EIP-2718 (Typed Transaction Envelope) (link), REP-0008: Sponsoring transaction (link) and several protocol improvements.
The hardfork is scheduled to take place on the mainnet around 7:00 UTC February 26th, 2024 at block 32367400. If you are running a mainnet node, please upgrade your node to this version before that block.
Full Changelog: v2.6.2...v2.7.1