Screen flickering in Windows 11 is usually caused by a display driver issue or incompatible app. To determine whether a display driver or app is causing the problem, check to see if Task Manager flickers.

If Outlook detects a problem with an add-in, you can uninstall and reinstall the add-in. If that doesn't solve the issue, contact the company that supplied the add-in. For most add-ins, you can find the company that supplied the add-in by selecting File > Add-ins.