IIRC, Brexit won by 51%. But 100% of UK exit EU. Biden did not get 100% votes in election yet he took 100% of the presidency from Trump.You assume that most people in Donbas wanted to be ruled by Moscow rather than Kyiv.
That may be true, but was any plebiscite ever held to ascertain it?
Moreover, even if a majority of people in Donbas wished to leave Ukraine, why should that mean that Russia must get all Donbas?
Let's suppose that 51% of people preferred to belong to Russia rather than Ukraine.
Why should Russia get 100% of Donbas rather than, say, 51% of it?
I believe that 'Donbas separatism' could be more fairly resolved by dividing Donbas rather than handing it all to Russia.
Should EU take 49% of UK back? Should Trump resume his 48% share of POTUS?