Our manual restore process uses --use-memory=464G for our 2+TB database otherwise it takes hours for the Prepare stage.

But recently we had a SST due to node failure which seems to use the default --use-memory=100MB which then results in the Prepare stage taking hours.
This severely impacted our Time To Recovery.

It should be possible to set the preferred use-memory size in a configuration file which can then be read by wsrep_sst_mariabackup.sh or by "mariadb-backup --prepare" as suggested by @Marko Mäkelä