The Cross of Military Merit stamp block was issued in October 2023.
The print run was 450,000 stamps so there are 75,000 blocks in total
On offer here is the First Day Cover (FDC) with a Kyiv cancellation.

From the Ukraine Post Office Philatelic Bureau >

The Cross of Combat Merit was established by the President of Ukraine on 5 May 2022 to recognise servicemen of the Armed Forces of Ukraine and other military formations formed in accordance with the laws of Ukraine for: outstanding personal bravery and courage or an outstanding heroic act during a combat mission in conditions of danger to life and direct contact with the enemy; outstanding success in commanding troops (forces) during military (combat) operations. The highest military award of the UPA and UGVR, the Cross of Military Merit, designed by the famous Ukrainian artist Nil Khasevych, was used as a model for the award. The President of Ukraine's "Cross of Military Merit" insignia is made of silver with gilding and looks like a straight equilateral cross with the Badge of the Princely State of Volodymyr the Great in the centre. Among the first to be awarded the military decoration were General Valerii Zaluzhnyi, Captain Vladyslav Kalievskyi, Sergeant Dariia Mazurenko, Lieutenant General Yevhen Moysiuk, and Colonel Oleksandr Okhrimenko. The design of the Cross of Military Merit was created by Oleksandr Lezhnev. The author of the postal issue is Volodymyr Taran.