No FirebasePlugin appear in windows with cordova-plugin-firebasex

Hi, I’m using cordova-plugin-firebasex for Ionic3, calling directly the api as specified here, something like

(<any>window).FirebasePlugin.logEvent('view_item', {some: "property"});

But no FirebasePlugin appear in windows, no problem with other plugin, any idea?
These are significant dependencies in my config.xml

    <plugin name="cordova-plugin-androidx" spec="^1.0.2" />
    <plugin name="cordova-plugin-androidx-adapter" spec="^1.1.0" />
    <plugin name="cordova-plugin-firebasex" spec="6.1.0" />
    <engine name="ios" spec="5.1.1" />
    <engine name="android" spec="8.1.0" />