Conversion between QQuaternion and Euler angles has issues in special cases

In certain cases (related to gimbal lock?) I'm getting inconsistent results moving between quaternion and Euler angle representations.

E.g.:

QVector3D eulerAngles1(90.f, -90.f, 0.f);
QQuaternion quaternion1 = QQuaternion::fromEulerAngles(eulerAngles1);
QVector3D eulerAngles2 = quaternion1.toEulerAngles();
QQuaternion quaternion2 = QQuaternion::fromEulerAngles(eulerAngles2);
qDebug() << eulerAngles1;
qDebug() << quaternion1;
qDebug() << eulerAngles2;
qDebug() << quaternion2;

produces

QVector3D(90, -90, 0)
QQuaternion(scalar:0.5, vector:(0.5, -0.5, 0.5))
QVector3D(89.972, 0, 0)
QQuaternion(scalar:0.707279, vector:(0.706934, 0, 0))

And it isn't a matter of ambiguity. Those two quaternions are two totally different orientations. Is it toEulerAngles() where it goes wrong?

Also, does the following description in the documentation apply?

Creates a quaternion that corresponds to a rotation of eulerAngles: eulerAngles.z() degrees around the z axis, eulerAngles.x() degrees around the x axis, and eulerAngles.y() degrees around the y axis (in that order).

As far as I can interpret what I'm seeing, the order seems to be the opposite, y-x-z.