1 🚀 产品观察 TechCrunch 2026-06-30 💬 WhatsApp now lets you reserve usernames WhatsApp推出用户名保留功能，3-35字符可选，正式版年内上线 WhatsApp username can be between 3 to 35 characters. whatsapp 用户名 隐私功能 社交媒体 meta