What does 'Donbass, whom the Ukrainian army has been bombing for the last 8 years' refer to?

Russian chess supergrandmaster Sergey Karjakin (Pro-Putin, but Ukrainian-born) says in tweets here and here to international master Kostya Kavutskiy:

Have you also collected money for the residents of Donbass, whom the Ukrainian army has been bombing for the last 8 years? You can come there and go, for example, to the Alley of Angels, which was built in honor of the children of Donbass who died from the shelling of Ukrainian criminals. Still funny?

What is the meaning exactly of Ukraine was bombing Donbass for 8 years? In particular, I checked Wikipedia Russo-Ukrainian War, and it looks like just 1 year: 2014–2015 war in Donbas.