I think we don’t have a way to customize this popup. We just provide the content of it, and the layout is managed by IntelliJ. I will double check
Do you know that we recently introduced a context action for each issue ? You can Alt+Enter on an issue, select ‘SonarLint: Show rule description’ and it will bring you to the Issues panel with a detailed description. You can also click on it in the little popup that appears on top of an issue as shown in your screenshot.