http://www.pcgamer.com/mercy-nerfed-ana-buffed-in-the-latest-overwatch-ptr/

Blizzard is testing some changes to two of Overwatch's healers: Mercy—currently regarded as overpowered and a must-pick in all situations—is getting nerfed, while the healing sniper Ana is getting a small buff. Here's what's changing:

Mercy's Resurrect is the focus of her changes. The ability now has a cast time of 1.75 seconds (up from 0 seconds), and can be interrupted by knockbacks, stuns, and Sombra's hack. In addition, Mercy's movement speed is reduced by 75 percent while casting Resurrect. To slightly offset the nerf, Resurrect's cast time is removed while Mercy's ultimate, Valkyrie, is active.