After 2 months (!) she came to me with the phone. Somehow she now had ads on her lockscreen, her default browser was hijacked by some other browser app with ads, and multiple apps had persistent notifications and were running continuously. Among them AVG anti-virus, some cleanup tool...
I have no idea how they got there. Probably because they pop-up in Ads with texts like "YOU NEED TO INSTALL THIS".
My grandma can't differentiate between an Ad like that and a serious System update notification.
It's stuff like this that leads people to just "give up" and buy an expensive Apple device. For all their faults at least they protect you from this kind of nonsense. The Lenovo is just the same, really. A profound disrespect for their own users and the usability of their own product.