We've setup Elasticsearch and Kibana (7.5.0) to provide AuthN/AuthZ via an OpenID Connect provider, which seems to be working fine. However, our OIDC is configured to use the user's email as their preferred_username, which Kibana then populates its Profile/Logout popup (top-right of browser screen).
Our email addresses, by chance, are quite long and this is causing the Logout link of the popup (and the latter part of our usernames/email addresses) to render off to the right of the browser screen, with no way to click it (other than knowing that one can "Tab" to the link and hit "Space"/"Enter"), which isn't such a great user experience.
This appears to be an artefact of the popup being rendered with a set width and in a set position on the screen (and the username not being wrapped to multiple lines when it hits a certain length).
We've worked around this for now by using a claims.pattern in the elasticsearch.yml for the security realm to extract just the "local name" (i.e. before the "@") of the email address and this has let the Logout link re-appear in the popup for our users without causing apparent ill effects to the AuthN/AuthZ mechanisms.