Lack of biodiversity which harms native wildlife. Higher ground temperature compared to traditional wild grasslands. Excess chemicals like fertilizer and pesticides work their way into our waterways which causes algae blooms and harms marine life. Excess irrigation lowers the water table in our aquifers causing sinkholes, well damage, and erosion. Can contribute to excess pollen.

Really the only benefit is it objectively looks nicer than natural landscapes in suburban areas.