This really hurts.
Devourer has one niche of being a power untamed dps pet; and it's not even the best at it on a golem, just more convenient in fights. I can understand a much smaller decrease in it's dps, but this is a wild swing at something not even over-performing. Significantly reduces the pet's viability from acceptable near-top placement to the lower half of the pack. It's a 0.5 to 0.3 coeff nerf on it's only damage skill, for anyone not familiar with the family type.
I've always loved the devourer pets and seeing it actually usable again after 10 years has been awesome. But it's such a short lived joy given it's been 3 months and it's going back into the dumpster.