In the URI, we embed username/password as well as the database URL/port. Without the flag [–tls], whatever later commands result in "Error: Server closed the connection", which hints at using the flag [–tls]. However, when using such flag, whatever later commands lead to "(error) NOAUTH Authentication required.", which is untrue as we already embed Username/password in the URI.
Said in other words, [redis-cli -u ] isn't compatible with flag [–tls]. As far as I know, there is no possible work-around.