volgens Jaswant Tak.
Yes I guess there is a bug, it always says same message "Check database unicode" while everything database and all tables are utf8_unicode_ci
I temporary continued by changing return type to 'true' in lib/dml/mysqli_native_moodle_database.php for
function setup_is_unicodedb()
changed return $return; to return true;
But there is a bug for sure.
Thanks