The Tree of Savior site has been updated with a new post to lay out big changes coming for all of the healing classes in the game. This is part of the overall "intense balance" pass that the team has been working on for the past several months. There is no specific information about when update will be deployed and the pass is still considered a work in progress.
Healing classes in Tree of Savior currently heal based on the "receiving character's capacity for HP recovery". This will change, however, when the update is deployed to being more dependent on the healer's abilities and skill level instead.
Ranged classes will also see some changes, most notably to skills for overall increases to damage, changes to cast times and new attributes added.
Check out the Tree of Savior site to learn more.