you need to add

camera.rotation.order = 'YXZ' // default 'XYZ'

in your init() function

reason: rotation matrix multiplication order

you can see detalised info here: https://en.wikipedia.org/wiki/Euler_angles#Rotation_matrix

also if you add this:

const axesHelper = new THREE.AxesHelper( 15 )
//axesHelper.renderOrder = 1;
axesHelper.material.depthTest = false;
scene.add( axesHelper )

in init() it will show world axes (and will be always on top of all objects) i needed that while cheking your code so maybe you also will need it in future