The search icon (search.png) is built in to the recipe book texture, unlike other usages of the sprite

This could be considered the cause of MC-164258, and if not closely relates to it.
The mangifying glass (referred to as search.png when used elsewhere) is built-in/hardcoded onto the recipe book texture (recipe_book.png), instead of using it's own unique sprite texture.

Steps to Reproduce:

1. Go to the following file path (or where ever Minecraft is installed):
   C:\Users[user]\AppData\Roaming\.minecraft\versions[latest_version]
2. Right click the latest [version].jar] file, and open it in a file explorer (7zip or winrar)
3. Go to the following path inside the jar:
   assets\minecraft\textures\gui
4. Open the recipe_book.png in any image viewer

Observed Behavior:

The search icon will be built into the texture.

Expected Result:

The texture would use a unique sprite icon, like all other elements of the recipe book. This is specifically expected, because the same exact magnifying glass texture is used as a sprite icon elsewhere (see assets\minecraft\textures\gui\sprites\icon shown below).

Screenshots/Videos:

View of the recipe book texture: