With the update to Sequoia 15.5 my Finder sidebar only showed iCloud and Shared. When I go to Finder Settings and select the Sidebar tab it shows the items that used to be shown. I have toggled showing the side bar and restarted my Mac and no change.
I was able to readd Documents to the sidebar but attempting to read others fails.
OK, finally figured this out. It was the Favorites that were not showing in the SideBar. When I tried to re-add items I accidentally dragged my Documents folder to the iCloud section by mistake. Cmd-Dragging other folders to the iCloud section did not work (no real surprise I suppose)
When I finally tried Cmd-dragging a folder to the Favorites section of the Sidebar all my old favorites showed up with it.
So problem solved.