Reuters quotes Bruno Le Maire. “The move from 4G to 5G changes many things at a technical level. It means that the most sensitive information are not only in the core networks but also in the antennas. We must protect this sensitive information.”
Le Maire supported a last-minute amendment to an unrelated bill that was aimed at Huawei. It was blocked by the Senate but will likely be tried again.
As far as I know, nothing in 5G makes it significantly more vulnerable to attack.