I wonder if it has different implications for different types of adblocking, then. A DNS-level block doesn't modify any copyrighted data, unless they're contending that the addresses returned by DNS servers are copyrighted. And that would seem to potentially pose major hurdles for the functionality of the internet.

I also wonder how it's made distinct from an addon that does something like block malware on a website. Surely that must be modifying copyrighted data too? Are some modifications allowed, I guess? Surely if something like an accessibility addon modifies the data, that's acceptable, right?