Monitoring is forced in newer versions of CCleaner. Meaning it will still run even after you tell it not to unless you install an older version.
https://www.howtogeek.com/361112/heres-what-you-should-use-instead-of-ccleaner/
A HUGE issue with CCleaner version 5.33.
https://www.howtogeek.com/326742/ccleaner-was-hacked-what-you-need-to-know/
And Piriform which makes CCleaner was bought out by that SHIT Antivirus company AVAST. Which is known for Loading there software to the hilt with Bloatware. AVAST antivirus Free edition has 15 yes 15 different scanners in it that constantly monitor and run in the background. And that's not including the actual antivirus software which monitors and scans automatically.