Hi,

This is a WordPress Transient feature. The Transients API in WordPress allows developers to store information in your WordPress database with an expiration time. This helps improve WordPress performance and speed up your website while reducing overall server load. This work like cookies but is more powerful than cookies.

To safely manage and delete, please install the Transient Manager plugin: https://wordpress.org/plugins/transients-manager/

Regards,
PenciDesign.