The answer to 'why is my landscape lighting overgrown' is that your landscape lighting has become overgrown due to the natural growth of plants, shrubs, and trees around the fixtures. Over time, the vegetation surrounding the lights can encroach on the fixtures, blocking the light and causing the lighting to appear overgrown.
This is a common issue that many homeowners face, especially as their landscaping matures. The overgrowth can reduce the effectiveness of the lighting, making it less visible and potentially creating safety hazards. To address this problem, you'll need to regularly maintain and prune the vegetation around your landscape lighting fixtures.