I assume the commenter is referencing the Russian use of the letter Z during their illegal invasion of Ukraine.
The Latin-script letter Z (Russian: зет, tr. zet, IPA: [zɛt]) is one of several symbols (including “V” and “O”) painted on military vehicles of the Russian Armed Forces involved in the 2022 Russian invasion of Ukraine
22 January 2024 (sh.itjust.works)