There are many special achievements in "Assassin's Creed: Visions", and the Scavenger achievement is one of them. To do this achievement, you need to hide 5 corpses in haystacks. Hiding in haystacks will activate Special assassinations where the enemy's corpse is automatically dragged into a haystack also count.
How to get the Scavenger achievement in Assassin's Creed Vision
Scavenger
The achievement requirement is to hide 5 corpses in haystacks
Hiding in a haystack and launching a special assassination that automatically drags the enemy's corpse into the haystack also counts; the same can be done with a hay cart, but it has a maximum corpse storage limit