User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-26467247-20201114083031/@comment-1038387-20201114124104

^MassUpload. It's the tray and arrow symbol in the editor. It allows drag and drop but not edit summaries (or upload name changing). It's apparently the native, vanilla successor; the MultiUpload extension is currently unmaintained and so may not work flawlessly.