You’re probably fine.

The reason you didn’t wanted magnets near technology before is because we relied on magnetic fields for stuff, so magnets distorted those uses. Nowadays we usually don’t have any magnetic parts on a phone, so unless you have a super strong magnet extremely close to the electronics you should be fine.

Specifically CRT monitors were tiny particle accelerators that shot electrons to a coat of phosphorescent material, they used magnets to redirect the electrons to hit the correct pixels at the right time. So putting a magnet nearby would pull the beam in a different direction distorting the image and shifting it’s colors (because the electrons were now hitting different color pixels). It was not irreversible, usually removing the magnet is all you had to do, but sometimes you might have magnetized something and the beam would remain crooked for a while.

The other thing that would be affected by magnets were hard disks, your PC might still have one so you might not want to put magnets near it, but our phone doesn’t. HDs stored information using magnetic fields into a disk, similar to a DVD except using a tiny needle that would magnetize the disk in one direction to write a 1 and on the opposite to write a 0. Taking a magnet near that would essentially erase all of the data in that disk. Modern storage use very different methods for storing data that don’t depend on magnetism, so you’re fine.