Am I understanding this VS Code API behavior correctly? Non-default *object* settings (when provided) are always merged?

I'm working on a VS Code Extension, and I think maybe I'm missing something in the docs, or else the behavior I'm seeing just isn't specified there, and my assumptions are wrong...?

I've defined some default settings for my extension, like so...

package.json

"contributes": {
    "configuration": {
      "title": "ToggleSettingsChanges",
      "properties": {
        "toggleSettingsChanges.settingsToToggle": {
          "scope": "resource",
          "type": "object",
          "default": {
            "window.zoomLevel": 2,
            "editor.fontSize": 22,
            "terminal.integrated.fontSize": 16,
            "scm.diffDecorations": "none",
            "workbench.statusBar.visible": false,
            "editor.cursorBlinking": "solid",
            "workbench.activityBar.visible": false
          },
          "description": "[ snip ]"
        }
      }
    }
  },

extension.js

// In the "main" method that runs when a command is activated:

const config = vscode.workspace.getConfiguration("toggleSettingsChanges");
const settingsToToggle = config.get("settingsToToggle");
const inspectedSettingsToToggle = config.inspect("settingsToToggle");

console.log("settingsToToggle:", JSON.stringify(settingsToToggle), "\n\n")
console.log("inspected settingsToToggle:", JSON.stringify(inspectedSettingsToToggle), "\n\n")
return;

In the Extension Host instance, I can tweak and adjust the settings, to include this:

User or Workspace Settings JSON

// ... 
"toggleSettingsChanges.settingsToToggle": {
  "editor.fontSize": 11,
  "pumpkins_are_great": true
},

In the console output, I'm seeing the following:

settingsToToggle: {"window.zoomLevel":2,"editor.fontSize":11,"terminal.integrated.fontSize":16,"scm.diffDecorations":"none","workbench.statusBar.visible":false,"editor.cursorBlinking":"solid","workbench.activityBar.visible":false,"pumpkins_are_great":true} 

inspected settingsToToggle: {"key":"toggleSettingsChanges.settingsToToggle","defaultValue":{"window.zoomLevel":2,"editor.fontSize":22,"terminal.integrated.fontSize":16,"scm.diffDecorations":"none","workbench.statusBar.visible":false,"editor.cursorBlinking":"solid","workbench.activityBar.visible":false},"globalValue":{"editor.fontSize":11,"pumpkins_are_great":true}} 

For the settingsToToggle line, I expected to see only the following settings:

{"editor.fontSize":11,"pumpkins_are_great":true}

It seems that if you provide an object default, any configuration provided is merged with that object, instead of replacing it entirely.

Is that the case? Have I missed this in the documentation?

It seems to me that a value (even an object) would be overwritten, and not simply merged.