You are talking about the entire taskbar going from top to bottom on the left, right? If so, this is not a Windows 11 feature. Do you run third party UI modification software.
Some common ones are like: Start11, ExplorerPatcher, StartAllBack, TaskbarX. Do you have any of those?
Otherwise, do a clean boot using this instruction: https://support.microsoft.com/en-us/topic/how-to-perform-a-clean-boot-in-windows-da2f9573-6eec-00ad-2f8a-a97a1807f3dd
Make sure you follow the instruction closely and do NOT disable the Microsoft services.
Then see if you still see also happens in clean boot. If not, then it is 100% from third party.