Hunter Pet's damage decreases in PVP

I’ve noticed that some pet-related abilities inexplicably reduce their damage after entering BGs and Arenas. I will mention as an example the skill “Kill Command”, in Open World, as you can see in the skill’s tooltip (I tried to upload the screenshots, but i couldn’t), it causes 2702 damage, however, when entering PvP scenarios, the same skill causes 2313 damage. I’m not sure this is a BUG, ​​however I haven’t found anywhere why this damage is reduced.