If I have this correct:

• US, Ukraine, and Russia never signed on to the pact to ban cluster munitions
• Cluster munitions would be highly effective at clearing out Russia's entrenched defensive lines
• Ukraine is specifically requesting the munitions from the US
• Western artillery ammo is starting to run short, so cluster munitions are needed to buy time until artillery shell production ramps up next spring
• Russia is extensively using cluster munitions in Ukraine right now, and their munitions have a much worse dud rate than the western cluster munitions, so there's an argument that preventing Russia from being able to use their shittier cluster munitions is better in the long run

It sucks, but welcome to war