What is the biggest problem WhatsApp currently has?

 The biggest problem WhatsApp currently has:

• While most messengers offer a one-time QR code confirmation before allowing you to talk without a smartphone, WhatsApp Web bothers you at every opportunity. The Web service isn't an app in and of itself; instead, it acts as a remote WhatsApp version with your smartphone as the primary device. Your smartphone will continue to function if it is connected to mobile data. Otherwise, put it out of your mind!
• WhatsApp Web is blocked if your smartphone's battery is low or turned off. When power-saving features put the WhatsApp Web service to sleep, the same thing happens. If you wish to use WhatsApp Web when you go home from work, you'll need to totally re-authenticate yourself and disconnect from your work PC.

Read More: Can WhatsApp be hacked?