Xtrabackup in Docker FROM percona/percona-xtrabackup:8.0 for MySQL 8.33 on docker fails with "[ERROR] [MY-012592] [InnoDB] Operating system error number 13 in a file operation."

MySQL & MariaDB Percona XtraBackup
4

I would do some basic diagnosis. Try mounting the mysql data volume into a plain container and see what the permissions look like from inside. That might give some insight.

Well, /var/lib/mysql should be user:group mysql:mysql