u/rebulast please let us know if this is intentional before I go and do a "transmute for daikyu multishot mod" thing (which we're still waiting on Baro to bring, btw)
Umbra Forma Blueprints are an intentional reward drop for Railjack missions in the Veil Proxima region (harder enemies, better rewards)! Wires may have crossed to have it drop on Earth, which is not intentional.