Default during tooltip, when hovering over a tab, a title and a link to the resource appear. But it is possible to add a page thumbnail there.
To do this, open the tab “chrome://flags/” and find the desired parameter by hashtag
#tab-hover-card-images or by name “Tab Hover Card Images”.
After that, give it a value “Enabled” and click on the pop-up button “Relaunch”. The browser will restart and you can test the feature by hovering over any tab and seeing the page preview.