Yes, magnets can have a negative impact on mobile phones as they can interfere with the built-in compass and GPS position reader inside the phone, which can lead to navigation and orientation problems. They can also affect the operation of other phone components, such as the touch screen or Hall sensors, which can cause issues with the phone's functionality. Therefore, it is important to avoid storing the phone near strong magnets and avoid carrying magnets in pockets with the phone.
For more information, read the article on dangerous magnets.