Under your apps, Recently visited shows the sites you visited last, one tile per site, up to 12.
It is built from your history on your Mac, and it is never shown in private windows.
To remove a site from it, clear it from your history. See History and the Library (krodium.com/help/history-and-library) and Clear browsing data (krodium.com/help/clear-browsing-data).
Still stuck? Write to [email protected].