Done both ways, whichever is most accessible. No big issue.

Here is my response in the other posting of this.

Wiring through the backsplash just under the uppers is typical, no issues there. However the black connectors need to be inserted fully into the light fixture and the wires entering must not be exposed, the sheathing must also enter the box. Would also take the kink out of that one wire.

Graham

Better done from the backsplash. Wiring inside the cabinet would be ugly. Whole wire should be clamped inside fixture with no individual wires showing outside.