It appears to be nothing more than a reckless gesture to piss off the Russians.
What is Russia going to do, invade Ukraine?
Ukraine has been firing Himars, Storm Shadows and other Western supplied weapons into Russia — primarily Belgorod and Crimea
Crimea is occupied Ukrainian territory, not Russian territory
Ukraine was not firing HIMARS-based missiles, Storm Shadows, and other Western supplied weapons into Belgorod. That is the whole policy change here. No longer is Ukraine expected to just take punches and be barred from shooting at the aggressor. Now they can use western supplied weapons to destroy Russian assets in Russia.