1. Reduced market demand: After the blueberry mask has been sold in the WeChat merchant channel for a period of time, the market demand may be reduced due to various reasons such as poor product effect and reduced consumer interest.

2. Increased competitive pressure: With the passage of time, the competition of WeChat business has become more and more fierce, and various mask products have emerged one after another. Blueberry mask may be squeezed by other new products, resulting in a decline in its sales.

3. Changes in the agency system: The agency system in WeChat business may have changed, resulting in the original agent no longer acting as the agent of blueberry mask, but a new agent or a direct manufacturer selling it directly.

4. Product quality problems: If there are serious quality problems or negative news about the blueberry mask, consumers may lose trust in the product and reduce their purchases.

5. Other reasons: For example, changes in the team of WeChat business, changes in agency relationships or adjustments in business strategies may all lead to WeChat business stopping making blueberry masks.

To sum up, there may be many reasons why WeChat merchants don't make blueberry masks, which need specific analysis.