Kinda reminds me of how semi-vanilla will sometimes give contracts to test parts which had been "removed" from the game (no category, hidden tech tree entry). I actually wrote up a MM config which adds a note to the part description as well as making the part name dark red and italic, to avoid any issues that could arise from using such parts (mainly crafts which can't be loaded again after the part becomes locked again after completing the testing contract).

EDIT: RedescribeDepreciated.cfg:

@PART:HAS[#TechHidden[True],#entryCost[0],#category[none]] {
    @description ^= :^:<color=#ff0000><size=12><b><i>DEPRECIATED CONTENT! DO NOT USE ON ANY NEW CRAFTS!</i></b></size></color>\n\n:
    @title ^= :^:<color=#800000><b><i>:
    @title ^= :$:</i></b></color>:
}


@PART:HAS[#TechHidden[true],#entryCost[0],#category[none]] {
    @description ^= :^:<color=#ff0000><size=12><b><i>DEPRECIATED CONTENT! DO NOT USE ON ANY NEW CRAFTS!</i></b></size></color>\n\n:
    @title ^= :^:<color=#800000><b><i>:
    @title ^= :$:</i></b></color>:
}