That's probably integrated speakers. Those can have quite powerful magnets. If it has old spinny hard drives, those have magnets, too. Sometimes the lid also has a magnet if there is a hall effect sensor for detecting if it's closed.

Usually it's hard to find a magnet that'd be strong enough to make electronics inside a laptop malfunction without breaking the case open. Your regular fridge magnets are too weak for that kind of application, so are the ones usually found in glasses cases. And if you happen to be an owner of a chonky magnet, you probably already know the thing is dangerous.