IDK.. but Ubuntu doesn't call their product Debian. They call it Ubuntu.
If OVH wants to take Ubuntu and call it OVH Linux, they can do that.. and they won't need to pay Ubuntu anything.
OVH is being asked to pay for a license because they refuse to rename it, and they refuse to distribute it unmodified.
OVH could also distribute it unmodified, and then package their changes into a deb package that they tell customers to install. Or they could simply allocate severs depending on which OS a person selects (so Ubuntu will work unmodified).
The fact is, they have several options to comply with Ubuntu's trademark policies.. but they've chosen to do none of those things.