"Historians contend?" Usuallly, whenever that phrase is used in other news stories, it means that some historians have a theory about something - a theory that others may dispute. For example from recent news stories;
Pre-war Lithuania was home to a thriving Jewish community of more than 200,000 people, with Vilnius a hub of learning known as the "Jerusalem of the North".
But historians contend that around 195,000 perished at the hands of the Nazis and local collaborators under the 1941-44 German occupation, nearly the entire Jewish population.
Historians contend that no single event caused the revolution on continental America inclusive of her 13 colonies. It was instead a series of event that led to the war.
Historians and economists, for example, have long disputed the cause of a mid-nineteenth-century spike in Southern productivity. Economists argue for agricultural innovations, such as new cotton seeds, while historians contend that greater levels of violence drove heightened production.
Some historians contend the 1848 song [Oh! Susanna] is actually an early, subtle anti-slavery song.In each case the use of the phrase means that there is a novel, possibly controversial assertion made by historians.
The decimation of Vilnius is a well-documented fact. If the specific number 195,000 is in dispute, then the paragraph should have been rewritten as "Virtually all the Jews in Vilnius were murdered by the Nazis and local collaborators..."
This is nothing less than a subtle form of Holocaust revisionism, given the imprimatur of a major wire service that newspapers throughout the world use as authoritative.
Worse yet, this is an AFP boilerplate. The exact same sentence was published in 2016 in another AFP story about Vilnius.
(h/t Jewdah Maccabee)