I put my tools and armor in a chest just before i logged of. When i logged on again my netherite head, pants, shoes and elytra hade disappeared. 
No other items seams to have disappeared from any other chest and there are several other chest in the area. During that session i had upgraded my gear to netherite and enchanted it with mending. But i hade done the same with 2 of my tools and chest armour and they are still here. 
No one has been on the server between my logging of and on.