I hadn’t heard the term (in the form “ruscist”) until listening to “Bayraktar” this morning—as you might gather, it’s a portmanteau of “Russian” and “fascism.” Ukrainian and Russian pronounce “fascism”, so they rhyme. The Russo-Georgian War in 2008 is believed to have popularized “Ruscism”, though it seems that the term has gained more popularity now.
It is also noteworthy that, in Russia (and possibly in Ukraine), the Nazis were commonly called “fashisty”, rather than “natsisty,” which was the reverse of the English phrase. Today, the term “fascist,” in America, is more of a promiscuously used political term by those on the Left to describe people they don’t like. Russia and Ukraine have a different set of invaders, so I think “fascists” are still very closely tied to them.