I didn't follow closely, who kept Snake Island before special operation started, and who is
keeping it now?
It was one of those amusing fabrications that the Western media got involved in early on. Like the 'Ghost of Kiev' lady who took out a whole Roosian air wing in her modified Pitts Special fighter plane (with graphics supplied by a video game.)
In the Western press, the Ukrainian 'defenders' told the Rooskies to F-off, mounted bayonets, grabed their entrenching tools, and fought to the last man. In reality, they surrendered and were returned to Ukraine with a promise to not participate in the struggle any more. Probably most of the neglected the pledge (at gunpoint from the swastika guys) I would guess, and was chalked up as an example of the early false hopes that the Russians had about the disposition of the Jewish funded CIA-run enemy.
Answer, the Russians or their proxies did not have it prior to the war. From what I can tell they had it but don't have it now. The (rather questionable) story from the Russian side is that the fought off an attack recently, but then abandoned the island anyway. Add this to the list of things which make me wonder how much of this whole conflict is made up out of whole cloth on BOTH sides of the info war.