Why Russia shifts target to Donbass from Ukraine?

The Russian prime minister has shifted his attention from the main cities of Kyiv to the Donbass. The Donbass themselves want separate independence from Ukraine. Why is the Donbass so unhappy with Ukraine? The deputy chief of the Russian army made a big statement and said that the first phase of the military operation in Ukraine has been completed and now the Russian army will focus on the complete independence of the Donbass.