I made this Heavy Desolate Leather farming guide to help out players who want to farm the leathers instead of buying them from the Auction House. I traveled around the Shadowlands to search for places with a high density of mobs which I can kill and drop Heavy Desolate Leather. Below you will find a list of places I think are the best for farming Heavy Desolate Leather.
All skinnable mobs can drop the 5 new skinning materials, so you will basically farm the same mobs for every leather.
Heavy Desolate Leather
Don't forget to enchant your gloves with Enchant Gloves - Shadowlands Gathering! This enchant brings skinning time down from 1.5 seconds to 0.5 seconds. (works with herbalism and mining too)
Bastion - 1
Farming Languishing Etherwyrms and Starved Etherwyrms around the marked area is also a great way to get a lot of leathers. They are needed in one of the starter quests in Bastion, so this area will be pretty busy at the start of the expansion. (which can be good if no one is skinning them)
Maldraxxus - 1
Maldraxxus - 2
Kill Virulent Pests around the marked area. They are a bit spread apart, but the respawn rate is fast, you will never run out of mobs to kill.