Reported by User:IagoQnsi from EN WP:

"Hey, in the past week or two I've noticed a weird issue with the Page Curation tools. The "Mark as Reviewed" button, which is normally a checkmark icon, has been showing the icon from the "Next" button instead. Here's a screenshot:

The issue only occurs when I'm not hovering over the button -- when I hover over it, it correctly shows the checkmark icon. The issue just seems to be that this one image file is the wrong image: https://en.wikipedia.org/w/extensions/PageTriage/modules/ext.pageTriage.views.toolbar/images/icons/normal/icon_mark_reviewed.png