The product description on AliExpress disappeared for the following reasons:

1. Platform policy adjustment: AliExpress may adjust the product description rules, causing some sellers to be temporarily unable to view or edit product descriptions. In this case, you can pay attention to the official announcement of the platform to understand the relevant policies and make modifications as required.

2. Product description violation: Your product description may violate the platform regulations, such as containing sensitive information, exaggerated publicity or infringement. In this case, AliExpress may temporarily hide your product description until you modify it to comply.

3. Technical failure: AliExpress may have a technical failure, causing the product description to not display properly. In this case, you can try to refresh the page or contact AliExpress customer service for technical support.

4. Sellers delete it by themselves: If you accidentally delete the product description, you can find the relevant product in the AliExpress backend, re-edit and add the product description.

5. Authorization issues: If you operate AliExpress through an agent or a third-party platform, you may need to contact the agent or third-party platform customer service to find out if there is an authorization issue.

To ensure that product descriptions are displayed normally, it is recommended that you follow the AliExpress platform regulations, avoid illegal descriptions, and pay attention to platform policy adjustments in a timely manner. If you have any questions, please contact AliExpress customer service for help.