After upgrading LiteSpeed from 4.x to 5.0, existing maintenance plans appear with name (Legacy) at the end.
This is by design.
All plans created in version 4.x will function in the 5.0 version. However the plans will have (Legacy) appended to the end of the name. This is to determine which plans were created in 5.0 and which were not. New plan create under the 5.0 version will not have (Legacy) appended at the end of the name.
Note, there is no way to rename the maintenance plans to exclude (Legacy).