There are a lot of environmental impacts created by far grass. For a start, they create substantial damage to local biodiversity. Real grass is home to many kinds of insects and other animals, as is the the soil beneath it. Other animals such as birds rely on those insects for food. Fake grass is a habitat and food source for nothing, and damages the soil beneath it.

Healthy plant covered soil is also a natural carbon sink, so the mere existence of fake grass contributes to CO2 buildup. The production and installation of fake grass is also carbon intensive.

Fake grass eventually degrades and requires replacement, and despite manufacture claims, recycling it is difficult and often practically impossible. The degradation of fake grass is also a source of microplastic pollution, which can be carried on the air or leach into the soil, and eventually reach water sources.

That's just a brief summary, there's plenty of more comprehensive information available online. The stuff is quite frankly another disaster for the environment waiting to happen. A ban can't come soon enough. There are plenty of better options for those that need an alternative to natural grass.