I still don’t know the cause and the solution of the problem, but I have found a patch, a solution. It is not ideal because the problem is reproduced again but while.
It is simply a matter of reinstalling wordpress, in the update panel reinstall the same version that is installed.
I think the problem has something to do with the API REST, because when it fails in the health of the site it also indicates that it has found a problem with the API_REST. When reinstalling the WP that alert disappears
