Sometimes, drawers will turn purple and black. They still function exactly the same, but they don't reset until you replace them or turn them with a crescent hammer. Shift right clicking on their item side fixes the half drawers but not the full drawers. The photo is with Storage Drawers Extras installed (that's all I was near at the time) but it can be reproduced with any normal drawer. Happens in world with just Forge & Storage Drawers. It's important to note that it only happens to a select few blocks, but this happens consistently. After being fixed, it stays normal for quite some time, until eventually I come back and the same few blocks have turned purple again.

Forge 1.12 - 14.21.1.2443.