They were a large source of coronavirus disinformation and vaccine disinformation. In this tweet below they were spreading disinformation around vaccine deaths to boost their vaccine at the expense of others. They were including all deaths after vaccination, regardless of whether a vaccine caused a death.
Ukraine in particular has been a target of their disinformation campaigns for many years. Much like in the US, Russia has tried to undermine Ukrainian elections and sow chaos in Ukrainian society. It helped fuel the anti-vaxxer movement in Ukraine.
There have been no deaths causally associated with the mRNA vaccines in the US. 9 deaths causally associated with the Johnson and Johnson vaccine from Thrombosis with Thrombocytopenia Syndrome in the US.