I discovered this recently when my housemate complained the WhatsApp iPad app was useless for some basic features that worked on their iPhone. Then we discover

I discovered this recently when my housemate complained the WhatsApp iPad app was useless for some basic features that worked on their iPhone. Then we discovered it was not an official app. I’ve been resetting all passwords shared with my housemate and am rethinking how I share sensitive information. The kicker is anyone on the other end of a message to or from an unofficial app doesn’t know their messages may have be compromised. I thought I was safe(ish), assuming only official clients were available in app stores.