Unexpected behaviour of FULL JOIN

The option FULL JOIN works as an INNER JOIN. This is missleading, because you expect the result of a FULL OUTER JOIN or an error message.
RIGHT OUTER JOIN -> Ok
RIGHT JOIN -> Ok
LEFT OUTER JOIN -> Ok
LEFT JOIN -> Ok
FULL OUTER JOIN -> Ok, error message
FULL JOIN -> Not Ok, like INNER JOIN
MySQL Community Server 8.0.33 has the same missleading behaviour.