Make sure you use the latest version Turn Off the Lights browser extension in your web browser. You can easily test this, with uninstall the extension and install it directly from the original add-on website (Chrome Web Store, Firefox extension, Opera extension, Microsoft Edge on the Microsoft Store or on the official Turn Off the Lights website).
The basic steps to solve this issue:
1. Restart the web browser
2. Remove your cookies and cache files
3. Disable the other browser extensions you have installed except Turn Off the Lights
4. Reinstall the Turn Off the Lights Browser extension