Some was domestic, some was from obscure new nations, most notably Macedonian teens, and various groups in Russia.
Well, an analysis has been published in The Proceedings of the National Academy of Sciences (PNAS), about the actual effect on votes, and the answer is very little if any:
If the goal is profit, then one will preach to the converted, particularly on the right-wing, because that is where the money is.
ConclusionCoordinated attempts to create political polarization in the United States by Russia and other foreign governments have become a focus of public concern in recent years. Yet, to our knowledge, no studies have systematically examined whether such campaigns have actually impacted the political attitudes or behaviors of Americans. Analyzing one of the largest known efforts to date using a combination of unique datasets, we found no substantial effects of interacting with Russian IRA accounts on the affective attitudes of Democrats and Republicans who use Twitter frequently toward each other, their opinions about substantive political issues, or their engagement with politics on Twitter in late 2017.
Of course, teasing out politics and profit are always problematic.