I’ve used the older (free) versions of CCleaner for years without (AFAIK) any issues.
I don’t let it anywhere near the Registry or update Drivers.
I recently (by mistake) let Windows update my mouse driver …. the mouse immediately started misbehaving. Seems Logitech has removed most mouse drivers from their Support page and rely on Windows to supply legacy drivers. Not good.
I use CC to clean Browsers’ caches (even the Browsers that apparently shouldn’t be running). I run Firefox which clears it’s cache when it closes, but belts and braces.
CC also cleans junk from Applications I select in the CC list.
I know that most of this stuff is doable manually, but CC is a one-click solution so saves a lot of time and hassle.
Sadly, Avast acquired CC in 2017, so who knows what ‘extra’ telemetry is now going on behind the scenes.
Ches