CNBC reports that Meta has begun replacing Llama 4, its previous flagship open-source model, with the proprietary Muse Spark across WhatsApp, Instagram, Facebook, and Meta's line of smart glasses. Muse Spark debuted in April 2026 as the first model from Meta Superintelligence Labs, the unit Mark Zuckerberg assembled with high-profile industry hires. According to CNBC, the model matches Llama 4 Maverick's performance while using ten times less compute, making it practical for real-time use on constrained hardware like smart glasses. Meta's shift to a closed proprietary model marks a notable departure from its Llama open-source strategy; the company says it hopes to open-source future versions of Muse Spark.