What is Russia's UTC+12 time zone called?

Russia's UTC+12 time zone is called Kamchatka Time.

It is named for the Kamchatka Peninsula and is also known as Petropavlovsk Time. Its standard offset is UTC+12:00, or nine hours ahead of Moscow Time. The zone covers Kamchatka Krai and Chukotka Autonomous Okrug, including Petropavlovsk-Kamchatsky and Anadyr.

Russia's time-zone history makes this answer easy to confuse. In 2010, Kamchatka and Chukotka were shifted into Magadan Time during a nationwide restructuring. When most of Russia moved clocks back in October 2014, the separate Kamchatka Time zone was restored.

Kamchatka Time has no seasonal daylight-saving change. Vladivostok, Magadan and Yakutsk are neighboring Russian zones, but they are one, two and three hours behind Kamchatka Time respectively. The IANA database represents the region with identifiers including Asia/Kamchatka and Asia/Anadyr.