Official WhatsApp messages are protected by end-to-end encryption. When you use a third-party mod, there is no guarantee that your messages remain private. The developers of the mod could potentially intercept and read your data. How to Get a Dark Aesthetic Safely

💡 Your privacy and data security are more valuable than a custom theme. Stick to the official version of WhatsApp to ensure your conversations stay private and your device remains secure.

Go to Settings > Chats > Theme and select "Dark."

On AMOLED displays, black pixels are essentially turned off. A pure black interface can noticeably reduce battery consumption.