The official WhatsApp Desktop application is on macOS 10.13.6 (High Sierra). The current official requirement is macOS 11 (Big Sur) or newer. Current Status Report
Older versions do not receive security updates, making your chats vulnerable. whatsapp for macos 10136
: The Firefox Extended Support Release (ESR) is highly optimized for older OS ecosystems. The official WhatsApp Desktop application is on macOS 10
Apple stopped providing security updates for macOS High Sierra years ago. Consequently, major software developers have shifted their development focus. whatsapp for macos 10136