https://www.bleepingcomputer.com/news/microsoft/windows-10-2004-external-displays-go-black-when-drawing-in-word/

Microsoft says that external displays might go black if Windows 10, version 2004 users try to draw in apps including but not limited to Microsoft Office Word and Whiteboard.

After the affected external monitors go black, customers will see that their graphics controllers are being marked as having issues in Device Manager.