This is an old post elsewhere, but someone had a similar problem. There was one recommendation to delete a different plist, com.apple.sidebar.plist, but that doesn't exist in Ventura anymore and may not in Monterey. The OP's final solution was to reset permissions on his home folder.
I had a hard drive failure and am temporarily using a machine which can only be brought up to El Capitan. I have a sidebar problem that is driving me crazy. The configuration of the sidebar favorit...
apple.stackexchange.com
That article provides a ilnk with instructions on what to do, but it may be a bit dated. It was last updated in 2020 for Catalina. But maybe this will get pointed in the right direction. Meanwhile, if it hasn't been tried, use Onyx to do some cache cleaning to see if that helps.