I think Savathun has been being completely honest with us since her crystallization. Yeah, she’s the queen of lies and the hive god of deception, but we KNOW that. We KNOW she’s a liar so we don’t believe anything she says. We are constantly told not to trust her. However, I think that’s exactly what she wants.
If a known liar lies, you won’t believe her. There’s no cunning in it. However, if a known liar suddenly tells the truth, you still won’t believe her. That’s the key. By telling us the truth, she’s making us deceive ourselves.