The global build discarder configuration gets saved, but it's never loaded.
On every restart, Jenkins 2.221+ will always start with the "Job Build Discarder" configured, which means
- Any custom global build discarder configuration is lost
- Users who don't want background build discarders get the default one.
The latter is especially annoying given that we warn against potential data loss in changelog ( https://jenkins.io/changelog/#v2.221 ) and upgrade guide (https://jenkins.io/doc/upgrade-guide/2.222/#old-builds-may-be-deleted-by-global-build-discarders ). Even one-time vigilance on update won't be good enough to prevent potentially undesirable outcomes.