Facebook acknowledges new Messenger battery drain issue, fixes it
Yesterday, David Marcus, who leads the Messenger team at Facebook, acknowledged this latest issue, while also saying that the problem was "fixed server side." In order to avoid the issue, Marcus says, you'd just have to restart the Messenger (or Facebook) app on your phone or tablet.
For now, we can't know if restarting the Messenger and Facebook apps eliminates the battery drain issue for everyone. In any case, it looks like Facebook is constantly monitoring problems of these kinds, and it's obviously willing to try and fix them as soon as possible.
source: David Marcus (Twitter) via Android Central