I recently had to bring on a new server to my cluster. But the admin installed xtradb 8.0.30 is that version compatible with version 8.0.27?
Yes, xtrabackup is backwards compatible.
mysql Ver 8.0.29-21.1 for Linux on x86_64 (Percona XtraDB Cluster (GPL), Release rel21, Revision 250bc93, WSREP version 26.4.3)
8.0.27-18.1 Percona XtraDB Cluster (GPL), Release rel18, Revision ac35177, WSREP version 26.4.3?