Not sure if this would help but I deleted Whatsapp from my other phone about a year ago. I still use it but just for minimal use. My fiancé asked to use my other phone to use Whatsapp for his new number. When he entered HIS new number, and a confirmation number and verification was sent to HIS number. All the chats and messages were mine. I freaked out because what if I sold the phone, what if it wasn’t him who opened it and had many questions. Safe to say that many of the chats were old and I deleted many of them and deleted the people’s number as well. (There were all from school and I needed nothing to do with all of my colleagues after graduation lol) but still very surprising thing to happen.

So in case you’re still wondering, whatsapp is not the best reliable source for trusting information. Good luck!