@Sandra_Martínez Why not use a custom field to differentiate the two?
Custom field: “Relates to”
Values: “Core project tasks”, “Other tasks”
Assign the values, and filter the views for those values. This would also ensure they get the custom field values automatically when you add them to the tab.
You can then even hide the field from the tab.
More inspiration on organising your tabs here: 🪄 Design magical tabs with group, sort, and filter!