Quick relevant copy and paste,
The following taskbar features are no longer available as of Windows 11:
- Support for moving the taskbar to the top, left, or right of the screen[7]
- Support for changing the size of the taskbar or its icons
- "Time" is not displayed in the calendar when clicking on the "Date/Time" on taskbar
- Scheduled events are not displayed in the calendar when opened
- The option to show or hide Windows shell's tray icons (Only third-party icons can be hidden or shown)
- All settings and shortcuts in the taskbar's context menu (Only a shortcut to the taskbar settings area of the Settings app is available.)[7]
- The network and audio flyouts have been consolidated into a new settings flyout
- "Some icons in the System Tray", although Microsoft doesn't specify which[1]
- Support for third-party taskbar components (deskbands)[1]
- The upward swipe gesture for jumplists
- Ability to move the system tray from the primary monitor[8]
- The People button (The "Chat" button powered by Microsoft Teams takes its place.)
- The News and Interests panel (The "Widgets" panel serves the same purpose.)
- Action Center (Two separate flyouts take its place: "Notification Center" and "Quick Settings")
- Support for showing one icon per app window the taskbar (Reinstated in May 2023; option merged with showing labels[9])
- Support for showing windows labels on taskbar (Reinstated in May 2023; option merged with separating window icons[9])
- Support for bringing an app into focus by dragging a file to its button[7] (Reinstated in February 2022 insider builds)[6]
- Task Manager can no longer be opened by right-clicking taskbar (Reinstated in September 2022 insider builds)
- Ability to peek at the desktop by hovering the mouse cursor over the Show Desktop button[10]
- Ability to display the seconds on the current time removed[11] (Reinstated in November 2022[12])
- Support for adding toolbars such as the Quick Launch Bar (apart from 3rd party software)
- Expanding Taskbar to two levels[13]
But see post