Thanks for providing the details.
I have logged in an check the site and have seen the issue you mentioned. The fixed widget is using a third party plugin for it implementation and as what I can see, the plugin should be able to detect when the current view is outside the main container so that the widget will not float above the footer area but it is not doing this which is causing the issue.
We suggest getting in touch with the plugin developer about this due to the fact that there is simply no way to account for all of the potential variables at play when using another developer’s plugin. Because of this, any questions you have regarding setup, integration, or troubleshooting any piece of functionality that is not native to X will need to be directed to the original developer.
Thank you for your understanding.