Don't recall saying anything about a tax.

From upthread, you wrote:

As I've pointed out, there is much more than 'tariffs' going on in trade. The media constantly mentions tariffs but largely ignore everything else.

Like extra taxes.

...in referring to the penalties imposed under the DMA. Some supporters of Trump's tariffs have tried to position those penalties as being "taxes" in disguise. But they're way too large. Taxes are generally charges that are imposed for the purpose of, and with the expectation of, raising revenue - but these are so big that they simply will not really raise any revenue, but instead force compliance (or more drastic changes).

At any rate, your point is only partially valid. Does Microsoft have to release Windows source code to operate in Europe? No, they don't. There's a line between ensuring interop and company secrets.

Does Microsoft need to release Windows source code to ensure interoperability under the DMA? Actually, let's step back - does Apple need to do that? Your article doesn't use the term "source code," and indeed does not any specific type of thing that Apple needs to provide in order to "open up" to interoperability. Is there anything to indicate that Apple is, in fact, being asked to release more than what Microsoft does in order to ensure interoperability?