Everyone needs a break sometimes. It’s a chance to step back, examine what’s going on, take a few deep breaths, all of that good stuff. Overwatch‘s closed beta also needs a break, and is going offline for an extended break starting on December 10th and lasting until sometime in January. The exact date of re-activation has not yet been announced or determined.
The stated reason for the break isn’t that there’s something intensely wrong with the game but that it gives the development team time to step back, examine the collected data, and make adjustments to the game without any new information coming in. If you’re in the testing, there’s no need to worry, as you’ll still be in the testing when the closed beta re-launches in January. Everyone wins, unless you were planning on using the test as an excuse for avoiding your family during the holidays.