Ok but I don't try anymore from CB activity.
I saw that all the pages created from a CB link in a menu created the global metadata of the site instead of taking the one put in the metadata option of the CB page.
When i see source code by CTRL + U of a page linked to a CB link in public, the meta description is always that of the global site.
This behavior is created only with CB links.
This is why the description metadata of the CB page does not load in CB activity.
This is why I ask you to create a CB page in public on your side or to control the description of your registration / login page by having modified the meta.
To hide them, I had already purged them but that hadn't changed anything.
I hope to be clearer, it's not easy to express clearly