Ubisoft has confirmed it is "actively working" on a fix to address the "crouch and lean spamming" currently affecting competitive play in Rainbow Six Siege.
Unscrupulous players are spamming the crouch and lean buttons to evade return fire. Here's a quick video of the technique in action - check out the jittery kill-cam at the end.
"Recently, we have seen a rise of players encountering abusive crouch and lean spamming," said community manager "UbiNoty" in the official subreddit (thanks PCGamesN). "To counter this, the team is actively working on how we want to approach the problem and planning our next steps.