WhatsApp will stop supporting 18 Android and 3 iPhone models in 2025 due to changes in compatibility with older operating systems. Affected devices include Samsung, Motorola, HTC, LG, and Sony models, with updates beginning January 1 for Android KitKat users. iPhones running iOS earlier than 15.1, such as the iPhone 5s and 6 series, will lose access starting May 5.