What's with CleanMyMac X?

It's from a company that is known for shady marketing ploys. It's not necessary and may even be harmful. Do not install it on your computer. If you have installed it, remove it according to the developer's instructions.

See also this article for more information:

Effective defenses against malware and ot… - Apple Community

Avoid it. Your Mac is quite capable of looking after itself and doesn't need 'cleaning'. Programs like this are quire liable to remove files which are actually needed.