Recently Google added a new experimental feature that displays a small info card when you hover over a tab in Chrome. Similar to Microsoft Edge’s tab hover card implementation, Chrome 74 will show a preview image of the associated web site. In future builds you will also be able to enable the Tab Hover Card Images setting to see image previews of the site represented by the tab when you Hover over it. At this time the code to display images has not been added to the Chrome 74 build, but the actual functionality to display image previews is forthcoming.
Source: https://www.bleepingcomputer.com/news/security/like-microsoft-edge-chrome-is-getting-tab-hover-card-images/