The answer to 'why is my light fixture dimming lights' is that there are several common causes, including a faulty dimmer switch, loose wiring, or a problem with the light bulb or fixture. Dimming lights can be caused by a malfunctioning dimmer switch that isn't properly regulating the electrical current. It could also be due to loose or damaged wiring connections in the light fixture or wall switch. Additionally, the light bulb itself may be going bad or the fixture may have an internal issue.
If you notice your lights dimming, it's best to first check the dimmer switch and ensure it's functioning properly. You can also try replacing the light bulb. However, if the problem persists or you're not comfortable troubleshooting electrical issues, it's recommended to call a licensed electrician to diagnose and repair the issue. Electrical problems can be dangerous if not addressed properly, so it's best to have a professional assess the situation.