Not sure this is a result of upgrading to Ventura but I suspect it is not,
I cannot find a way to find out the size of iCloud folders that are containers of apps (use Pages as an example). For all other types of ‘standard’ folders in iCloud drive, I just right click and select info, but there is no such option for app containers
I have Calculate all sizes turned on in Finder (CMD+J) for all folders and it correctly displays all folder sizes in Finder in the Size column, including for the folders in iCloud Drive. It also always updates quickly for local folders so there’s no need for CMD+I on folders to find out the size.