Camera zoom in 2D map affected by latitude and window size

I need to control the camera zoom in an accurate way no matter how big is my browser window or what latitude I’m located in. Using camera setview.

If I create an entity (circle in example) in a specific coordinates and a radius, and I find a zoom altitude where my circle fits in 50% of the viewer, this zoom altitude value is not valid when I change my latitude.

Changing the latitude of my camera to a higher latitude place and drawing the same circle size, produces different viewer area even locating the zoom at the same altitude. Same happens if I change my browser windows size and viewer is resized.

I found no way to find a zoom mechanism which respecst the same aspect ratio with drawn objects no matter the latitude I’m working plus the size of my window.

Any explanation and if possible, a solution please?

Thank you very much.

Addendum: I use 2d map with terrain since I have to draw material based on elevation, in a pure 2D map with no terrain it doesn’t happen.

const viewer = new Cesium.Viewer(“cesiumContainer”,{
terrainProvider: Cesium.createWorldTerrain({
requestVertexNormals: true,
mapProjection: new Cesium.WebMercatorProjection(),
sceneMode: Cesium.SceneMode.SCENE2D ,
mapMode2D: Cesium.MapMode2D.ROTATE,