The answer to 'why is my lawn invasive plants' is that your lawn may be overrun with aggressive, unwanted plants that are outcompeting your desired grass and other plants. This is a common problem that can be caused by factors like poor soil quality, improper mowing or watering, and the introduction of invasive species.
Some common symptoms of an invasive plant problem include a patchy, uneven lawn appearance, the presence of weeds or plants you don't recognize, and a decline in the health and coverage of your desired grass. The best solutions often involve a combination of proper lawn care, targeted weed control, and potentially re-seeding or re-sodding portions of your lawn.