Workshop: https://steamcommunity.com/sharedfiles/filedetails/?id=2809207844
In 3.4.2, there's currently a bug with the subjugation war goal.
When you status quo, you're supposed to get a new vassal from the systems you have occupied, if there's at least one colony amongst those systems. Currently, the systems you don't occupy become your vassal (and all vassals of the defender also become your vassal) and the systems you do occupy become a new independent empire.
This mod patches the issue.
In 3.4.2, there's currently a bug with the subjugation war goal.
When you status quo, you're supposed to get a new vassal from the systems you have occupied, if there's at least one colony amongst those systems. Currently, the systems you don't occupy become your vassal (and all vassals of the defender also become your vassal) and the systems you do occupy become a new independent empire.
This mod patches the issue.