Since it’s an old version, even the developer no longer patches bugs or security holes. Newly discovered exploits in Android WebView or WhatsApp protocol will remain unfixed.
If you choose to download it, do so with caution: use a secondary number, back up everything manually, and stay active in community forums to hear about ban waves. And remember—you can always switch back to the official app if the mod becomes more trouble than it’s worth. Whatsapp Aero V8 40 Download Old Version