PMM Backups fail, says latest XtraBackup 8.4.0-4 is incompatible with XtraDB cluster 8.4.5-5.1

Here is the error I get when trying to perform a backup from PMM Console:

xtrabackup version “8.4.0-4” is not compatible with mysql version “8.4.5-5.1”: incompatible xtrabackup

WTH? If I installed the latest production software, why is there an incompatibility?