I'm not sure what you're showing us? Can you say more?
If that's actually what you're seeing on screen, 1) restart your computer and 2) restart Zotero in Troubleshooting Mode (Help → "Restart in Troubleshooting Mode…”), which temporarily disables all plugins, and see if it still occurs.
If that's actually what you're seeing on screen, 1) restart your computer and 2) restart Zotero in Troubleshooting Mode (Help → "Restart in Troubleshooting Mode…”), which temporarily disables all plugins, and see if it still occurs.