Well, that would likely depend upon exactly what was meant in this context.

World War One did end for the Russians when the Bolshevik revolution broke out, and of course that entire story did feature a lot of civil unrest. Of course, war didn't end for the Russians as they went right into the Russian Civil War, but that's another story.

For the Germans, large scale civil unrest did break out in 1918 and perhaps the best example of that is the Kiel Mutiny. This certainly factored into the closing days of the war for Germany including the political calculations that were being made by the government, the replacement of the monarchy by a republic, etc.

So in that fashion, that would be true.

This wouldn't, on the other hand, have been a factor for the UK or US. France did see some frontline discontent starting in 1917, but I don't think it can be claimed that such events were a factor for France as well. Of course, for the Allied nations in the war in 1918, as Germany collapsed, civil unrest at home could not be claimed to be a factor for the Allied nations anyhow, unless a person were to go on and argue that perhaps they influenced the nature of the peace.