If a developer leaves debug mode turned on in an environment, the user will begin getting JavaScript limit exceptions.Debug mode is a setting that enables more detailed logging and error reporting for Lightning web components. However, it also increases the size and complexity of the JavaScript code that is delivered to the browser, which can cause performance issues andJavaScript limit exceptions. The JavaScript limit exceptions are errors that occur when the browser reaches its maximum capacity for executing JavaScript code, such as memory heap size or script execution time. The performance of the org will not become slower each day, as debug mode only affects the client-side performance, not the server-side performance. The org will not turn off debug mode after 72 hours, as debug mode is a persistent setting that can only be changed manually by an administrator. A banner will not be displayed to the user indicating that the org is in debug mode, as debug mode is a transparent setting that does not affect the user interface. Salesforce References: Lightning Web Components Developer Guide: Debug Your Code, Lightning WebComponents Developer Guide: JavaScript Limit Exceptions