The answer to 'GFCI outlet dimming lights' is that a GFCI (ground fault circuit interrupter) outlet can sometimes cause lights to dim or flicker. This is a common issue that can have several potential causes, including a faulty GFCI, an overloaded circuit, or a problem with the wiring.
GFCI outlets are designed to detect ground faults and quickly shut off power to prevent electrical shocks. However, this sensitivity can sometimes cause issues with certain types of lighting, especially dimmable lights or LED bulbs. The GFCI may be interpreting the normal fluctuations in the electrical current as a fault, causing the lights to dim or flicker.