I used the file menu to tell lighroom to quit, the dialog that normally appears never appeared. I then hit the red 'x' button in the apple OS UI to close the lightroom window, at which time the dialog asking if I wanted to quit appeared and i selected yes. I then waited for the follow up dialog asking about backing up which never appeared, i sat waiting and then realized that multiple folders were selected on the left panel and when I clicked on a different folder the dialog finally appeared and lightroom succesfully finished closing. There should be either a warning that it can't close while multiple folders are selected or it should be able to close while that is the situation. Either way it isn't the first thing one thinks of, and if I was too impatient I might risk catalog integrity by forcing the sofware to quit via the OS.
macOS Monterey 12.5.1 (on a mac studio m1 ultra with 128GB ram)