Variants of a mold are catalogued separately, so each one has its own sets and minifigs. Check these too if something you expect is missing here.

• 19727pr0008 Minifig Head Special, Cube with Rear Ledge, Pixelated Light and 2 Dark Bluish Gray and Black Face Print (Mooshroom) Alternate of this part
• 19727pr0077 Minifig Head Special, Cube with Rear Ledge, Pixelated Black, Light Bluish Grey, Dark Bluish Gray Face Print Alternate of this part
• 19727 Minifig Head Special, Cube with Rear Ledge [Plain] this part is a print of it