The Kotaro release includes the Tripp hardfork on testnet. This release implements REP-0010: Introducing Rotating Validators (link), REP-0013: Propose Berlin EIPs on Ronin (link), REP-0014: Propose London EIPs on Ronin (link) and several protocol improvements.
The hardfork is scheduled to take place on the testnet around 7:00 UTC May 23rd, 2024 at block 27580600. If you are running a testnet node, please upgrade your node to this version before that block.
Full Changelog: v2.7.1...v2.8.0