Stating without context that "vaccines cause myocarditis" is indeed disinformation, because it encourages people to irrationally focus on a particular (edge-case) negative outcome, whilst disregarding the (common) positive outcome.

Add the context, and the potential for disinformation goes away: "Vaccines cause myocarditis, but overall at a lower rate than the disease itself. Additionally, the disease has many other, much more significant, risks that are mitigated by vaccination."

The point I'm making is that disinformation is a psychological effect. A statement can be factually true and still be disinformation ("100% of child abusers found to have consumed dihydrogen monoxide", etc.)