It's only a war crime if it comes from the Moscow Oblast region of Russia. Otherwise it's an unfortunate but necessary defense strategy.

What the hell

Considering that Ukraine is considering using them on their own territory which is already filled with more landmines than you'll be able to get rid of in a lifetime, I think that's their decision to make. They will be the ones dealing with the consequences of this, it's not as if they invaded someone else's country and used cluster muntitions on civilians of that country like, say, for example.....Russia...

Both Russia and Ukraine have been using Soviet-era cluster munitions since early in the war. The US made versions have a lower failure rate so it's preferable that Ukraine use those instead.