Does masturbation invalidate the fast in Ramadan, and is it obligatory to make up the days in which one masturbated, given that their number is unknown, and what is incumbent upon someone who did that while not possessing sufficient money for expiation?

Intentional masturbation is forbidden and invalidates the fast if it leads to ejaculation. Masturbation is even more prohibited during Ramadan (definition). For someone who masturbated out of ignorance of the ruling and its prohibition, their fast is not invalidated according to the most preponderant opinion. However, for someone who knew it was forbidden but was ignorant that it invalidates the fast, their fast is invalidated. The days on which the fast was invalidated after puberty must be made up (qaḍāʾ), but no expiation (kaffārah) is required, only making up the missed fasts. He is not obligated to inform his family about the reason for his compensatory fasting.