LCDs have no interaction with magnatism. People used magnets to flip EVFs, because back before iPhones made MEMS motion sensors cheap, they used sensors that simply worked off gravity. The magnet activated the switch, making the LCD think it was upsidedown when it was upright. Over time, especially if the magnet doesn't move much, it won't impart much magnatism on anything, and what little it does won't be enough to do anything adverse to an LCD or related components. Very little electronics these days are affected by permanent magnatism. Things change when that magnatism changes polarity often or a permanent magnet moves against a low voltage, heavily amplified trace without a feedback circuit (which these days is almost never).
Electronic design in the very few circuits that could be affected by magnetism or electromagnetic radiation when cell phones came into vogue. Magnets, even when moving, impart only a small fluctuation in most signal traces or wires, so it doesn't take much to design around these constraints. Almost all digital circuits are impervious to typical magnet induced current, or environmental EMI, because good luck getting a single short trace to absorb a 3.3v worth of magnetic induction from any magnetic or EMI source. (place a coil of high current, high voltage wire next to a wifi router. Odds are the range will be shortened, but it will still work reliably....unless you place it next to a 20K dimmer)