The effect of rice water depends entirely on its application. Rice water used on electronic devices and rice water used on hair have different outcomes.
Rice Water and Electronics: No Benefit, Potential Harm
Putting electronic devices in rice after water damage is ineffective and potentially harmful. Contrary to popular belief, rice does not effectively absorb moisture from internal components. In fact, it can hinder the drying process by preventing air circulation around the device, potentially leading to further damage. (https://www.reddit.com/r/applehelp/comments/9qcenu/psa_rice_is_not_for_fixing_water_damaged_phones/, https://discussions.apple.com/thread/8398497, https://discussions.apple.com/thread/253061504) Instead of rice, allow the device to air dry in a well-ventilated area.
Rice Water and Hair: Potential for Both Benefit and Harm
Rice water, when applied to hair, offers potential benefits due to its protein and nutrient content. However, overuse can lead to damage. The starch in rice water can draw moisture out of the hair, causing dryness and damage if used excessively. (https://www.reddit.com/r/longhair/comments/uhxh8k/is_rice_water_actually_good_for_hair/, https://www.quora.com/What-can-I-do-to-reverse-rice-water-protein-overload-I-used-rice-water-on-my-hair-twice-a-week-for-a-month-has-it-done-too-much-damage-already-Have-I-used-it-too-much-My-hair-is-straight-and-has-low-porosity) Moderate use may improve hair shine and strength, but excessive use can lead to dryness and breakage. Some individuals may experience negative effects more readily than others.
In summary: The damaging potential of rice water is context-dependent. It's ineffective for electronic device repair and can even worsen the damage. For hair, it may provide benefits, but moderation is crucial to prevent adverse effects.
