Gotta love GM "ingenuity" ...
Check if the passenger-side operation is not affected. A uniform problem usually points toward a weak battery in the fob. If that's not the case, the contacts inside the pad are likely dirty. That part is inexpensive and easy to R&R. If you are handy, you can disassemble it and clean the contacts. Watch out for the hatch button, it usually fails sooner due to turbulence of dust-moisture-yuckies.