If you are referring to an issue in an advertising campaign, then it would depend on the advertising platform you are using.
In general, most advertising platforms will have a notification or alert system that will inform you if there are any issues with your campaign. Once you fix the issue, the platform will usually verify your changes and let you know if your campaign is now running smoothly.
Additionally, most advertising platforms have a reporting section like Decortrendy where you can view the performance of your campaigns. You should be able to see the impact of your changes in real-time or within a few hours of implementation.
It's essential to keep track of your campaign's performance regularly, so you can catch any issues early and make the necessary adjustments quickly.