Some new silliness: let’s say you were in the midst of copying files. Now, when you close all Mac finder windows, this will also close the copy progress window. Since it is such an important window I think it is ridiculous that this window now closes also. (Example: if you were thinking of removing a drive, now you can’t tell when copy is finished since there’s no window, only the tiny progress circle in the sidebar.)
Anyway- The good news: if you are in the Finder, goto window> show progress window - and happily it will return.