So if Putin has his rockets or artillery fire on Ukrainians in the Donbass, you think they will not fire back?
First, the white flag is still a thing. It worked just great for Ukrainian regulars in Crimea.
Second, the shelling is mostly uniquely done by the Ukrainian forces whereas the opposite side is doing the counter-battery.
It is easily proven by the regularly posted maps of shelling by OSCE, wherein LDNR the population centers are getting hit and forests on the Ukrainian side. Data on casualties supports this conclusion because they are mostly women and children in LDNR and exclusively military in Ukraine.