I looked for more error reason with my haproxy and nginx but everything seems normal.

When sharing a facebook link with the odoo website the link https://www.facebook.com/sharer/sharer.php?u=https..."your odoo instance "is created correctly .

But if you tried to make a facebook message by reminding a part of your website with a link to one of your page ... facebook displays in the preview 127.0.0.1

It's strange and I do not have a solution

For information
web.base.url is set correctly with web.base.url.freeze false and proxy_mode True in system.
In the same environment networks my machines odoo 11 work but my machines odoo 12 make this mistake