Technically, a more direct analogy would be that some newspaper print on demand service exists, and the instructions for printing are distributed to the machines that print the newspapers, but are modified during distribution before the newpaper is printed by the reciever.

As much as I'm pro ad blockers, this seems like a reasonable reading of the law. An interesting way to convince yourself of this is to find a solid line that you could draw based purely on a set of principals grounded by some legal standard about what the difference between a desktop computer program, a downloadable JavaScript program, CSS and HTML really is in terms of how they cause a computer to act on the information.

That said, I think you could fairly reasonably find that section 69e of the copyright act (english translation [1]) applies to adblock software, though I'd imagine the plaintiff would probably argue that the use of an adblock software interferes with their interests.

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Section 69e Decompilation

(1) The rightholder’s consent is not required where reproduction of the code or translation of its form within the meaning of section 69c nos. 1 and 2 is indispensable to obtain the information necessary to achieve the interoperability of an independently created computer program with other programs, provided that the following conditions are met:

1. the acts are performed by the licensee or by another person authorised to use a copy of a program or on their behalf by a person empowered to do so;

2. the information necessary to achieve interoperability has not previously been made readily available to the persons referred to in no. 1;

3. the acts are confined to those parts of the original program which are necessary to achieve interoperability.

(2) Information obtained through acts as referred to in subsection (1) may not be

1. used for purposes other than to achieve the interoperability of the independently created program,

2. given to third parties, except when necessary for the interoperability of the independently created program,

3. used for the development, production or marketing of a computer program which is substantially similar in its expression or for any other acts which infringe copyright.

(3) Subsections (1) and (2) are to be interpreted such that their application neither impairs the normal exploitation of the work nor unreasonably impairs the rightholder’s legitimate interests.

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[1]: https://www.gesetze-im-internet.de/englisch_urhg/englisch_ur...