When I uninstall WhatsApp from Android device, would my chats'/msgs' data stay on device? so i made this stupid mistake of uninstalling whatsapp then giving away my phone without resting it to factory settings, so the other person now have my device, could he by a way or another retrieve my uninstalled whatsapp data? In other words, when we uninstall whatsapp, does all the data related to our whatsapp msgs and chats get deleted or do they stay in some form that could be retrieved? I don't know the guy very well so i don't trust him and i'd really appreciate to know what's what so maybe i could make a plan. Thank you.
There are two separate issues


Factory reset was not done , so it's technically possible to retrieve data but this would involve sophisticated methods not in the reach of an average person
As far as WhatsApp is concerned , when you uninstall , the data is  not accessible even on installing again since you need to authenticate the telephone number , which I presume it
s with you. WhatsApp database is encrypted making it more difficult to retrieve messages but your WhatsApp pictures, videos and audio can be accessed


IMO, unless the other person is very savvy technically, it's not a cause for concern but then in future do remember to encrypt your device and factory reset to ensure that others cannot access your private data