MariaDB Galera SST using mysqldump - mariadb

Question

Background:
I have a 3x server Mariadb Galera cluster that is happily working with mariabackup SST method, but recently have dumped a lot of legacy data out of tables (was 370GB+ now down to 75GB storage).
In order to shrink the database size to avoid such large SST requirements my understanding is mysqldump/restore could be used to achieve this. As such my thought process was to drop one of the servers from the cluster, and bring it back in with mysqldump SST method to shrink the disk usage. After this, I was then planning to force SST on the other nodes with the shrunken server as donor with mariabackup SST method again.
If my logic is flawed on the above please feel free to pull me up.
Problem:
After dropping one node and switching SST method to mysqldump, the server came up and made contact with the other nodes, but SST would fail.
SST Donor as Node 2, I get below logs on that node;
2023-02-16 21:02:40 9 [Note] WSREP: wsrep_notify_cmd is not defined, skipping notification.
ERROR 1045 (28000): Access denied for user 'backupuser'#'192.168.2.100' (using password: YES)
ERROR 1045 (28000): Access denied for user 'backupuser'#'192.168.2.100' (using password: YES)
ERROR 1045 (28000): Access denied for user 'backupuser'#'192.168.2.100' (using password: YES)
/usr//bin/wsrep_sst_mysqldump: line 128: [: -gt: unary operator expected
ERROR 1045 (28000): Access denied for user 'backupuser'#'192.168.2.100' (using password: YES)
2023-02-16 21:02:40 9 [ERROR] WSREP: Process completed with error: wsrep_sst_mysqldump --address '192.168.1.100:3306' --port '3306' --local-port '3306' --socket '/var/lib/mysql/mysql.sock' --gtid 'a98addba-189c-11ed-887e-4258cd7b8de4:687374620' --gtid-domain-id '0' --mysqld-args --basedir=/usr: 1 (Operation not permitted)
2023-02-16 21:02:40 9 [ERROR] WSREP: Try 1/3: 'wsrep_sst_mysqldump --address '192.168.1.100:3306' --port '3306' --local-port '3306' --socket '/var/lib/mysql/mysql.sock' --gtid 'a98addba-189c-11ed-887e-4258cd7b8de4:687374620' --gtid-domain-id '0' --mysqld-args --basedir=/usr' failed: 1 (Operation not permitted)
2023-02-16 21:02:41 0 [Note] WSREP: (a897af72, 'tcp://0.0.0.0:4567') turning message relay requesting off
SST Donor as Node 3, I get below logs on that node;
2023-02-16 21:24:01 8 [Note] WSREP: wsrep_notify_cmd is not defined, skipping notification.
mysqldump: Couldn't execute 'show events': Access denied for user 'backupuser'#'localhost' to database 'main_db' (1044)
ERROR 1064 (42000) at line 24: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'SST failed to complete' at line 1
2023-02-16 21:24:02 8 [ERROR] WSREP: Process completed with error: wsrep_sst_mysqldump --address '192.168.1.100:3306' --port '3306' --local-port '3306' --socket '/var/lib/mysql/mysql.sock' --gtid 'a98addba-189c-11ed-887e-4258cd7b8de4:687381861' --gtid-domain-id '0' --mysqld-args --basedir=/usr: 1 (Operation not permitted)
2023-02-16 21:24:02 8 [ERROR] WSREP: Try 1/3: 'wsrep_sst_mysqldump --address '192.168.1.100:3306' --port '3306' --local-port '3306' --socket '/var/lib/mysql/mysql.sock' --gtid 'a98addba-189c-11ed-887e-4258cd7b8de4:687381861' --gtid-domain-id '0' --mysqld-args --basedir=/usr' failed: 1 (Operation not permitted)
mysqldump: Couldn't execute 'show events': Access denied for user 'backupuser'#'localhost' to database 'main_db' (1044)
ERROR 1064 (42000) at line 24: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'SST failed to complete' at line 1
2023-02-16 21:24:04 8 [ERROR] WSREP: Process completed with error: wsrep_sst_mysqldump --address '192.168.1.100:3306' --port '3306' --local-port '3306' --socket '/var/lib/mysql/mysql.sock' --gtid 'a98addba-189c-11ed-887e-4258cd7b8de4:687381861' --gtid-domain-id '0' --mysqld-args --basedir=/usr: 1 (Operation not permitted)
2023-02-16 21:24:04 8 [ERROR] WSREP: Try 2/3: 'wsrep_sst_mysqldump --address '192.168.1.100:3306' --port '3306' --local-port '3306' --socket '/var/lib/mysql/mysql.sock' --gtid 'a98addba-189c-11ed-887e-4258cd7b8de4:687381861' --gtid-domain-id '0' --mysqld-args --basedir=/usr' failed: 1 (Operation not permitted)
For identification in the above;
192.168.1.100 is Node 1
192.168.2.100 is Node 2
192.168.3.100 is Node 3 (Though it's IP isn't listed in above)
Server version: 10.3.32-MariaDB-log MariaDB Server
I have confirmed that the backup user account and password in the "wsrep_sst_auth" parameter can be used from any node to connect to any other node via console (including itself) and even went as far as to drop a new database into Node 1 and explicitly add that user with full permissions before I tried to join it to the cluster again with the same results.
Node 1 has been rolled back to mariabackup SST method and successfully rejoined the cluster, but I would like to reattempt the above to shrink the disk usage if anyone is able to provide some guidance on why I might be seeing the above errors and additional options to try and resolve.