I suspect this happens because your fields inside the tab end up having the same name as the tab itself.
So, if you name tab Slider and then create Repeater Slider inside it, it will fail, even though Tab’s name or slug is not explicitly available to edit.
As user you can name your tab with tab at the end, so that automatically created name would have it, later you can change the Title of the tab.
But it should be fixed by developer by adding some unique suffix or at least “__tab”.
