I had a funny situation with kindle. It was connecting to the internet all the time, I enabled airplane mode and then it started complaining about it all the time.

Out of spite I added password to my wifi (I didn't have any and I even named my hotspot smth like "free" for my neighbors to use, wouldn't do that now).

To my surprise, some ~8months later I discovered my kindle to happily connect to my wifi. I'm pretty sure I would never enter the password there, because the kindle was the reason I added password to begin with. Maybe there is some more sane explanation than "kindle bruteforced my wifi", like a bug or some nuance in authorization protocol?

edit: it happened 7 years ago with kindle 2013 paperwhite.