Added Sufix to URL

Hello,
On every URL (except the backend) of my website appears a suffix (/?v=da7f24de4c8e) I don’t know what it means and I’ve been trying to remove it without success. It’s always the same, never changes the code after the ?v=
– I’ve changed the permalinks, rebuild them with no luck.
– I’ve deleted and created a new .htaccess file
– I’ve removed the super cache plugin and disabled all the plugins that could change the URL
– I’ve tried with a different theme.

Please, Anyone could point me in the right direction? Thanks in advance.
Regards

The page I need help with: [log in to see the link]