Certain operators have offers that include applications of which the consumption is not deducted from the data volume.
That practice, often called “zero-rating”, is not explicitly regulated by the net neutrality rules.
One part of the net neutrality rules generally specifies that Internet traffic should be treated in the same way.
It was clear that this meant that it is forbidden to allow zero-rating applications to continue at the normal speed, whereas other traffic was blocked or throttled (e.g. because the data volume in the bundle was used up).
But whether that rule also applied to a different way of billing, without blocking or throttling in an unequal way, was not clear.
The European Court of Justice has ruled that this is the case.
So there is a good chance that zero-rating offers are illegal and will need to be changed.