The Windows 11 taskbar does not support drag and drop, ie. you can not drag a file to a an app pinned to the taskbar and expect it to open, like on Windows 10.
If this is a workflow you are used to and do not want to give up, there is now an open source app that will bring much of the functionality back.
Windows 11 Drag & Drop to the Taskbar (Fix) fixes the missing “Drag & Drop to the Taskbar” support in Windows 11.
Windows11DragAndDropToTaskbarFix is a standalone app that lives in your system tray and works with the new Windows 11 taskbar. It does not change any system registry keys (except autostart for itself when manually configured) and does not inject any DLLs to other processes, so it’s a very portable solution.
The program detects if you’re currently pressing the Left or the Right Mouse Button and determines which icon on the taskbar you hover the mouse pointer on. If the cursor stays in the same area for a defined number of milliseconds – it simulates the Win+T hotkey and arrow keys in order to restore the intended window, using a quite complicated method. It also supports dropping files to the “Show desktop” button (bottom-right of the screen). The program supports multiple screens, auto startup, and has many configuration options.
Find the download at GitHub here and consider donating to show gratitude to the developer.