I've recently uninstalled CCleaner from several of my devices, all for the same reason.
When I uninstalled, there was no option to gather feedback as to why I uninstalled the app - so I thought I would come here to give that feedback.
I have always found the Piriform Tools to be good. CCleaner and Speccy were always my go-to tools when setting up a PC for myself or friends, and generally formed part of my over-all PC Setup with some of the decent AV tools. I considered them, especially CCleaner, to be fundamental tools.
However, over recent months I have noticed changes which I do not like - most notably are the popups on screen which vary from smaller popups near the clock to bloatware suggestions on update of the program.
It does feel that these notifications are almost daily. Between Black Friday Sales, offers to install X, Y or Z - it has gotten to a point where now the adverts feel constant. Maybe they're not, and I understand that revenue needs to be generated. But for a tool which is used infrequently, the sheer number of adverts outweigh the benefits of keeping the tool installed.
As a cleaner, it's a superb piece of kit. But as Windows progresses some of the tools are less and less important. The Registry Cleaner is one such tool. Even a search on here states that the tool isn't recommended for Windows 10 - but no such warning on the app itself.
But being an avid fan of CCleaner and the benefits it offers (especially on a PC owned by someone who has no idea how to use other ways of cleaning) meant that the app was always being kept on the system as it's better to have it than not. But now, with the constant intrusions, it just isn't.
There's other issues about this raised on here, and it may not be a big issue for most people - but for me the intrusions are just too much.
I'm sure I will download the most recent version as and when I need it, but for the most part I won't be keeping CCleaner installed on the computers just in case.