When backing up my W10 account, I noticed 6200 jpg files in C:/users/<user>/AppData/Local/Microsoft/WIndows/Notifications/wpnidm. Those files consumed 89MB of data impacting backup space and time. Request you purge that directory in your next CCleaner update. AppData is a hidden folder.
Reference: https://answers.microsoft.com/en-us/windows/forum/all/wpmidm-folder/a3bf9c67-0f62-420f-82e9-cea82395c07e
Maybe there are more things that could be purged from user AppData directories too... Thanks.