It would make more sense for Russia to bomb their own facilities in Belgorod. Why?

 Because then they can run this on TV all Across Russia saying that Ukraine attacked them and this way Putin could justify on TV to the Russian People using Tactical Nuclear weapons on Every city in Ukraine.

What would this do?

It would make every city he did this to including Kyiv uninhabitable because of nuclear radiation. It would end the war basically except for people who chose to die of radiation poisoning (at least in every habitable larger city.

OF course there likely would still be a Ukrainian insurgency out in the country where people would be less likely to die of radiation poisoning than in the radiated cities where everyone would die who stayed there from radiation poisoning. Because if they did this all food and water and living spaces would be radiated in all cities tactically nuked.

A tactical nuclear weapon usually makes an area about 5 to 10 miles in diameter gone which would be the city center of all larger cities in Ukraine. So, this might be what Putin has in mind now.