This used to be the the go to software for keeping the PC running well. The newest version, however, has turned me off the software forever. I choose what runs on my PC and when. I have ALWAYS set CCleaner to not run at start-up and never automatically. This new version doesn't obey that rule. It sets itself to start when the PC starts and changes any attempt to stop it. That action is how MALWARE operates. CCleaner is now MALWARE.
If you had read the changelog you would see that CCleaner Free is now able to give you automatic updating.
(That option only used to be available for Pro users who had paid for their CCleaner).
To enable this CCleaner now runs a background task to check for updates every 12 hours, which is what you are seeing. If you don't want that then simply turn off the automatic update option.
Go to - Options>Updates - and untick 'Keep Ccleaner updated automatically'.
If you are having problems turning that off then give a shout.