admin/environment/custom check/Asynchronous backups disabled

From MoodleDocs

Asynchronous backups provide a better user experience allowing users to do other operations while a backup or restore is in progress.

Asynchronous backups are enabled in new installs of Moodle 4.4 and will be enabled for all sites from Moodle 4.5 onwards. Synchronous backups will be removed from Moodle LMS the version after 4.5 LTS.