It is needed in summer to replace solar energy during the night. Gas power plants can be switched on and off almost at will, unlike coal or nuclear plants that have long startup and shutdown times. So the gas power plants are switched on at night in summer when the sun doesn't shine.

Also, the EU commission declared in February 2022 natural gas as a sustainable energy source, and the EU parliament confirmed this in July 2022. Sounds a bit bizarre, but the dates are correct.