Destiny 2 developer Bungie have made the armour shaders that feature in the game one use consumable items.
Armour shaders in Destiny 2 are cosmetic items that are applied to armour in order to give the players armour a different colour scheme. In the original Destiny, these shaders were permanent and could be obtained via loot drops and could also be bought from in game vendors.
Once you had unlocked a shader and applied it to your armour the effects of the shader would be permanent and the shader was tied to your account forever.
In Destiny 2 however, shaders are consumable items. If you have a shader applied to your armour but find another one you like the look of better, once the new shader is applied your old shader will be lost until you find it in another loot drop later down the line.
Destiny 2’s director, Luke Smith took to twitter to defended this decision about shaders in Destiny 2:
When you reach level 20, Shaders will drop more often: vendor rewards, destination play and endgame activities. (2/4)
— Luke Smith (@thislukesmith) September 7, 2017
With D2, we want statements like "I want to run the Raid, Trials, or go back to Titan to get more of its Shader" to be possible. (4/4)
— Luke Smith (@thislukesmith) September 7, 2017