Why Quaternion from inverted Euler angles not equal to inverted Quaternion from original Euler?

Could you explain please, why these two inverted quaternions are not equal:

Vector3 ev = new Vector3(x,y,z);
Quaternion q   = Quaternion.Euler(ev);
Quaternion iq1 = Quaternion.Euler(-ev);
Quaternion iq2 = Quaternion.Inverse(q);
if (iq1 != iq2)
{ Debug.LogWarning(" =( "); }

This warning prints every frame.
I expect, quat. from inverted Euler angles should be equal to inverted quat. from original Euler.

Yes have found out the same thing…
But no one replied here?