Seems like they're blocking French networks (ISPs?) instead of IP addresses, since GeoIP blocking was found insufficient by a German court. I struggled to understand their actual plans from their blogpost though, maybe someone else can interpret it better?

https://quad9.net/news/blog/au-revoir-france/

how? They use DNS to "block" access to websites by not resolving domain name, if they would have an other way to block a service they wouldn't need to ask DNS provider to do so