Problems with cookie compliance. Why?

I checked my site with cookiemetrix.com.

All ok in blocking cookies with my EU-cookie plugin except for one third party from FACEBOOK.NET that could install cookie and this is make my page.
I thought was the facebook pixel or something similar, and deactivated all plugins and checked the code.

I deactivated your plugin and all goes ok.
I re-activated it and again the facebook cookie is it.

Actually i have to deactivate the plugin and i pass the cookie consent test.

But i don’t understand why there is a cookie on the frontend of site when this app is used in backend to send the post to facebook.

Can you tell me how to workaround and where to put hands to remove this cookie??