These seem like a "Sure, why not?" rather than any kind of game changer, but IDK, maybe Ukraine has an anticipated need to stop small infantry groups...
Possibly Ukrainian military is saving the 600s for some specific operation they have in mind, or possibly they are using them but just keeping quiet...
They might not care about losing peasant conscript lives, but they've lost a hell of a lot of their actually trained & equipped infantry that they've...