Over the last year, Google has pressured Apple to adopt the RCS standard and help break down the artificial walls between messaging platforms. Apple remains adamant in its opposition, with CEO Tim Cook recently saying he would “love to convert you to an iPhone” user. Now, Meta's Mark Zuckerberg is using an advertisement for WhatsApp features to take a dig at Apple’s stubbornness.

On Monday, Zuckerberg shared on Instagram this new WhatsApp billboard, displayed at Penn Station in NYC. The ad mocks the ongoing green-bubble-blue-bubble debate, suggesting people instead switch to WhatsApp’s “private bubble.” Although this ad only uses the controversy as context, Zuckerberg’s caption for the Instagram post goes straight for Apple’s jugular (via The Verge).

The Meta CEO boats that WhatsApp is more private than iMessage, thanks to platform-agnostic end-to-end encryption, even in group chats. He also highlights how WhatsApp backups are end-to-end encrypted too, unlike iMessage. WhatsApp boss Will Cathcart went into greater detail in a series of tweets, explaining that people continue to text because of how iMessage works, even though more secure options like WhatsApp exist. He also highlights other privacy features which iMessage cannot rival, like view-once media and disappearing messages.

WhatsApp has 2 billion users worldwide, but it isn’t the most popular service in the US. A spokesperson for the company told The Verge that this new ad campaign will also show up on TV, digital video, outdoors, and on social media across the US.