'Access denied; you need (at least one of) the PROCESS privilege(s) for this operation' when trying to dump tablespaces
mysqldump requires at least the SELECT privilege for dumped tables, SHOW VIEW for dumped views, TRIGGER for dumped triggers, LOCK TABLES if the --single-transaction option is not used, and (as of MySQL 8.0.21) PROCESS if the --no-tablespaces option is not used. Certain options might require other privileges as noted in the option descriptions.