It’s from the 9/19 TWID actually:
On the PvE side, the Hunter’s Combination Blow melee in particular has been a little too hot, so we’re making some changes to make it more about damage than survivability.
Combination Blow
Rescaled healing from a flat 80 HP per kill to 100/80/60/40 per kill based on stack count.
No longer clears health and shield stun on kill.
Removed the 1.5 second internal cooldown on healing.
So they removed a non-existent cooldown on the healing factor and reduced the health recieved the higher your stacks are...
They do realize the most popular exotic with Combi is Assassin's Cowl, right?