Under-cabinet LEDs flicker, then dim intermittently

One under-cabinet LED fixture has started flickering and occasionally going dim. The others stay steady. It seems worse after the light has been on for a while, but I’m not sure whether changing the dimmer setting affects it.

What’s the safest troubleshooting order? I can turn off the breaker and check for dust, loose accessible connectors, or a visibly damaged wire, but I won’t open a powered fixture. The lights may use a separate driver, though I haven’t located it yet.

Could this point to a failing LED module, loose connection, overloaded or heat-affected driver, or an incompatible dimmer? The fixture type, driver location, and any recent electrical work seem relevant. At what point should I stop checking connections and call an electrician, and when is replacing the driver or entire fixture the better fix?