Is knowledge of its prohibition, or of the act being a fast-breaker, a condition for it to be considered a fast-breaker, such as in the case of masturbation?

A fasting person is excused for an ignorance that does not invalidate their fast if they commit an act that breaks the fast, and this ignorance is of the prohibition of the act and of its being a fast-breaker. So, whoever is ignorant of the prohibition of masturbation and of its being a fast-breaker, their fast is not invalidated by it. However, whoever knows of the prohibition of masturbation but is ignorant of its being a fast-breaker is not excused, because they were obligated to avoid what is unlawful, and their fast is invalidated. Thus, ignorance of a ruling is excused, but ignorance of the consequences of a ruling does not waive the obligation.