When using the IntegratedMesh3DTilesLayer add an option depth test against terrain (like in Cesium), to hide 3D Tiles objects that are occluded by the terrain.
https://cesium.com/learn/cesiumjs/ref-doc/Globe.html#depthTestAgainstTerrain
CesiumJS sample with depthtestagainstterrain = true (https://bertt.github.io/esri_issues/depth_test_against_terrain/index_cesium.html)
Esri Javascript SDK 4.29 draws all the 3D Tiles objects (https://bertt.github.io/esri_issues/depth_test_against_terrain/index_esri.html