What is causing Craft CP assets(JS/CSS) to appear in front-end pages?
those CP files are included by CpAsset asset bundle.

if your plugin asset bundle depends on CpAsset:

class YourPluginAsset extends AssetBundle
{
    public function init()
    {
        $this-&gt;sourcePath = __DIR__ . '/dist';
        $this-&gt;depends = [
         CpAsset::class,
        ]
     //....
    }
}


and if you register your plugin asset in frontend or backend template:

{% do view.registerAssetBundle("ns\\prefix\\YourPluginAsset") %}


or via controller:

 $this-&gt;view-&gt;registerAssetBundle(YourPluginAsset::class);


those file are added to that page automatically.