Which repositories are used by Plesk System Updates tool to update packages?
Plesk System Updates tool installs updates for each package from the repository from which this package was initially installed.
This mode is called "safe updates" and is used in Plesk by default.
To view which repository is used to update a package:
1. Go to Tools & Settings > Update and Upgrade Settings > All Packages tab.
2. Look at the Package column. For each package, the repository is displayed in the round brackets.