You have a point about the negative externalities, but insisting on using the word "subsidy" for that concept is just going to confuse people. That isn't the accepted meaning of "subsidy", in casual conversation at least.

Hmm — how else would you call it? As I understand it, future generations are subsidizing the price of our fossil fuels and internal combustion engines, making ICEs artificially cheap by not considering their environmental impact.

Subsidies do not have to be in the form of cash: many come in the form of tax breaks and I would consider this to be one such case.

It is just confusing to use the same word to suggest explicit assistance (cash, tax breaks, etc) and "failure to penalize". I guess mathematically they both represent a reduction in cost when compared to an alternative scenario (no subsidy and some sort of tax/fee for the externality) but they are different mechanisms and so it makes sense for them to have different words to describe them if you want to communicate clearly.

It gets far worse when you consider the total cost of wars to protect the flow of oil.

There were still wars before oil was a thing.

EVs don't pay carbon taxes either (which they should).

You’re arguing for carbon taxes on electrical generation. Entirely agree. This would push coal and natural gas out of the electrical grid generation mix even faster, making EVs even cleaner.