Bone rotation arround two axis is is changing size of the bone

[swafe]

When using rotation(Float3(1f, 0f, 0f), 90F) it works fine but when rotating arround x and y at once the rotated bone looks bigger.

modelViewer.asset?.let {
 val entityId = it.getFirstEntityByName(mBone)
 val boneTransformComponent = modelViewer.engine.transformManager.getInstance(entityId)

 var initialBoneTransfomationTranspose= transpose(Mat4.of(*initialBoneTransfomation))
 var matrixRotationXY= rotation(Float3(1f, 1f, 0f), 90F)

 val localTransformRotationXY = initialBoneTransfomationTranspose* matrixRotationXY

 modelViewer.engine.transformManager.setTransform(boneTransformComponent, transpose(localTransformRotationXY).toFloatArray())
 modelViewer.animator?.updateBoneMatrices()

The problem could be related to the weighting but I am not sure how to continue.