When setting the position/size of a windows with .position, if the new place is on a screen that have a different DPI it will not get the right size. You sometime need to set the position twice to move it to the expected position
You can test it with the following code which is a modified version of  [https://docs.unity3d.com/ScriptReference/EditorWindow-position.html]

 
{code:java}
// The position of the window is displayed when it is
// external from Unity.
using UnityEngine;
using UnityEditor;
public class PositionExample : EditorWindow
{
    Vector2Int p1;
    Vector2Int p2;
    bool showBtn = true;    [MenuItem("Examples/position")]
    static void Init()
    {
        GetWindow<PositionExample>("position");
    }    void OnGUI()
    {
        Rect r = position;
        GUILayout.Label($"Position: {r.x}x{r.y}({r.width}-{r.height})");        p1 = EditorGUILayout.Vector2IntField("Set the position:", p1);
        p2 = EditorGUILayout.Vector2IntField("Set the size:", p2);
        if (showBtn)
        {
            if (GUILayout.Button("Accept new position"))
            {
                r.x = p1.x;
                r.y = p1.y;
                r.width = p2.x;
                r.height = p2.y;                position = r;
            }
        }
    }
} {code}
set it to a position on the first screen with a size of 640x480 and then change the position to appear on the second screen. The size will not be the good one.