Hat-tip to Eurogamer for spotting this, and finding the video above in which a player charmingly describes the event as "very peculiar". Players of Call of Duty: Warzone have begun seeing a brief message appearing in the middle of matches which reads "KNOW YOUR HISTORY", words that appear in a burst of static and are accompanied by Russian text which apparently translates as "doomed to repeat it".
Every player in a group sees the message simultaneously, which is either a fun teaser or a frustrating distraction depending on whether it happens during downtime or while you're being shot at.
Infinity Ward's narrative director Taylor Kurosaki has suggested that Warzone will be a constant for Call of Duty from now own, even as other games in the series follow it, saying, "Call of Duty is a genre in itself, there are different branches in the Call of Duty tree, but they’re all connected in some ways. Warzone will be the through line that connects all of the different various sub-franchises of Call of Duty."
The next mainline Call of Duty game will be called Black Ops: Cold War, a fact that was confirmed by a Doritos promotion, and it's being made by Treyarch and Raven. Here's everything we know about Black Ops: Cold War.