My two cents: someone being ex-Hindu means to me that they’ve reasoned themselves out of the doctrine and dogma. My assumption is that this person would be skeptical and not believing in things such as reincarnation or the caste system.
On the other hand, it doesn’t mean they have shed their entire Hindu identity”. They’d still probably culturally celebrate and partake in festivities: just without that belief.
Dunno if it makes much sense but just my perspective as someone outside of the Hindu community.