CCleaner is fine. It is completely safe as long as you don't us its registry cleaning functionality. CCleaner's registry cleaning is much safer that that of other registry cleaners, bot none of them is completely safe. Moreover, none of them are needed.
However, most of what Cleaner does isn't needed. It doesn't hurt to use it, but don't expect it to make great imrovements to your performance; it won't.
I see that someone else here has said "it is not advisable to use thir-party apps." I completely disagree. Yes, some third-party programs are dangerous, but that doesn't mean they all are. You should avoid a third-party program that's known to be dangerous, not all third-party programs. I, for one, use many third-party programs under Windows 11, and I'm very happy with them.