If you've played Rainbow Six Siege in the past few weeks then you've probably come across Jäger players exploiting a glitch with his deployable shield. The glitch makes him nearly impossible to kill, and Ubisoft has been rushing to fix it. That fix is nearly complete, the developer said on Reddit on Friday, and a patch should be live in the next few days, which is good news.
Usually Jäger plonks his shield on the ground so that other defenders can use it as cover, but by following a series of steps players can get it to sit on top of their gun so that they can run around with the shield covering the upper half of their body. Their view is not obstructed by the shield, so they can still shoot as normal, but nobody else can shoot through it.
Basically, it breaks the game. If the Jäger player crouches behind cover then they are virtually impossible to tag, but they can still kill any attackers that come into view. As you'd expect, it's become pretty popular with a certain group of players.
Ubisoft has not set an exact date for the patch, but says it should happen "earlier in the week". For people that have had rounds ruined by the exploit, it can't come soon enough.