A user's laptop keyboard is distorted and no longer flat.

CompTIA A+ highlights that swollen or expanding batteries especially lithium-ion batteries can physically warp the laptop chassis, keyboard, or trackpad. This happens when internal chemical reactions cause the battery to swell. Distorted keyboards, bulging trackpads, and lifted chassis panels are classic symptoms of battery failure.

RAM and HDD issues do not cause physical deformation. A broken keyboard may malfunction electronically, but it will not bulge upward unless forced by something underneath typically an expanding battery.

The A+ safety domain also warns technicians not to puncture swollen batteries and to replace them immediately due to fire hazards.

Therefore, a failing (swollen) laptop battery is the most likely cause.