A lot of apps use SMS-based authentication to send you a One Time Password (OPT) as the second factor of verification. However, researchers have noted that that relying on SMS can be less secure, as hackers have been using techniques like SIM Swapping to redirect 2FA codes. To solve that problem, Instagram is working on a feature to send you 2FA codes through WhatsApp. App researcher and leaker Alessandro Paluzzi posted screenshots of this feature under development. 

— Alessandro Paluzzi (@alex193a) May 22, 2021 These screenshots suggest that Instagram will verify your WhatsApp account through an SMS-based code, which seems counterintuitive at first because the whole point is to remove text messages from the equation. Anyway, once you confirm your WhatsApp account, you can get 2FA codes on the chat app for subsequent logins. Notably, the screenshots suggest that WhatsApp won’t store any of your data. So, Instagram is not technically ‘linking’ two accounts here. While you’re at it, you might want to check out our guide for saving songs that are playing on Instagram Reels.