It's an old documentation, but this page discourages the use of hibernate.connection.release_mode: https://docs.jboss.org/hibernate/stable/core.old/reference/en/html/transactions-connection-release.html
We use hibernate.connection.release_mode = on_close in tests, and everything starts to fail if we don't.
We should check whether we have a problem somewhere, or if it is really needed (in which case we should document that and explain why).