Although Safari 15 mostly works for me it is not compatible with the Homebridge UI. When accessing that, logs will not show, the terminal does not function, and I cannot update existing modules or install new ones. I also think the new tab, bookmark, reading list Sidebar is a disgrace. Previously if the sidebar was open and I selected a bookmarked site or manually entered a url the Sidebar would close providing the whole window for use by the chosen site. If I closed the site by returning to the Start Menu the Sidebar would reappear, allowing a new selection.
Now I need to not only manually open and close the Sidebar, I must also manually select the Tab Group I want to work with (in most of my cases, Bookmarks) then manually close it when the site opens. When I later reopen the Sidebar it does not even return to my chosen Tab Group. I must again manually reselect the proper tab group.