Differential privacy does not anonymize your data. It's a (mathematically solid) instrument to make it coarse enough to only give up the part you want.

The EFF is completely correct in their assessment - there's no way to make your data anonymous and usable by the third party at the same time. The root issue lies elsewhere.

There's FHE, which does allow your data to be processed without accessing it, but it has prohibitive compute requirements and isn't practical for most purposes. I'm not sure if it allows the data to be usable enough without revealing it, either.