Crimea has undergone significant changes over the past six years. A large number of ethnic Ukrainians and Crimean Tatars — some put the total at 140,000 — have left the peninsula since 2014. Crimean Tatars complain of intimidation and oppression as one reason for moving. During the same period, some 250,000 people have moved from Russia to Crimea (Crimean Tatar leaders claim the influx is much larger). The inflow has included troops and sailors, as the Kremlin has bolstered the Russian military presence on the peninsula, deploying new submarines, surface combatants and combat aircraft among other things.
https://www.brookings.edu/articles/crimea-six-years-after-illegal-annexation
According to the Office of the Federal State Statistics Service in Crimea and Sevastopol, since 2014, 205,559 Russians moved to Crimea, of whom 88,445 settled in Sevastopo
https://jamestown.org/program/demographic-transformation-of-crimea-forced-migration-as-part-of-russias-hybrid-strategy/