This is the question posed within this NY Times opinion piece by Sean McMeekin, 'a professor of history at Bard College...the author of The Russian Revolution: A New History.'
The author writes that, before April 1917:
Because he returned home by way of Germany — and with the obvious cooperation of the German High Command — which was then at war against Russia and her Entente allies (France, Britain and, from April 6, the United States), allegations that Lenin was a German agent were immediately hurled by his opponents, a charge that remains controversial to this day. If it is ever proved that Lenin was acting on behalf of the German Imperial Government in 1917, the implications for our understanding of the October Revolution, and the Soviet Communist regime born of it, which lasted until 1991, would be profound. This would amount to the greatest influence operation of all time, making present-day concerns about Russian meddling in Western elections, including last year’s American presidential contest, seem tame in comparison. Was it true?
I'm just curious if any of the posters here know more historical details about this narrative and what the consensus among anarchists and communists on this notion that Lenin was a German agent is today.