When you add Project Roles via Jira Settings > System > Project roles, you can also configure default members for that role. When a role has default members, the role and members get added to any new projects that are created.

These roles and members are also added to any projects that are migrated into the cloud site. When migrating from cloud to cloud, this isn't always the desired behavior, as you are migrating existing configurations, permissions, and workflows into the new target site.

This suggestion is to allow the option to choose whether to add the roles and default members to the migrated projects.