'Access denied; you need (at least one of) the PROCESS privilege(s) for this operation' when trying to dump tablespaces
use --no-tablespaces
see mysqldump-Documentation

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.

and see documentation of param no-tablespaces

--no-tablespaces, -y
This option suppresses all CREATE LOGFILE GROUP and CREATE TABLESPACE
statements in the output of mysqldump.