RTCReporting file growing uncontrollably and consuming disk space and CPU

See if this helps . . . turn OFF "Share Mac Analytics" in the Privacy & Security pane of System Settings.

RTCReporting is a System Process that can not be deleted 

Upon further investigate,  from within Activity Monitor 

Below are the files that are open and in use  

If as you have mentioned “ Over time, this file grows uncontrollably—sometimes exceeding 60 GB—which gradually fills up my disk. “ 

This appears to be some Other Issues that  may need investigating 

/usr/libexec/rtcreportingd

/Library/Preferences/Logging/.plist-cache.a6yhlHQ0

/private/var/db/timezone/tz/2025b.1.0/icutz/icutz44l.dat

/private/var/root/Library/Caches/com.apple.rtcreporting/eventcache/cache.db-shm

/System/Library/CoreServices/SystemVersion.bundle/English.lproj/SystemVersion.strings

/private/var/db/mds/messages/se_SecurityMessages

/usr/lib/dyld

/System/Library/Frameworks/CFNetwork.framework/Versions/A/Resources/DafsaData.bin

/private/var/db/analyticsd/events.allowlist

/usr/share/icu/icudt76l.dat

/dev/null

/dev/null

/dev/null

/private/var/root/Library/Logs/RTCReporting/RTCReporting_messageLog_2025-05-14-03-23-50.txt

/private/var/root/Library/Caches/com.apple.rtcreporting/eventcache/cache.db

/private/var/root/Library/Caches/com.apple.rtcreporting/eventcache/cache.db-wal

/private/var/root/Library/Caches/com.apple.rtcreporting/eventcache/cache.db-shm

[ctl com.apple.netsrc id 8 unit 34]

To pursue this Further Investigate suggestion

To skip the Q&A session, just download the Application Etrecheck directly from the Developer. 

It’s a diagnostic tool that doesn’t change your computer at all. It gives you a clear and easy-to-read list of both your hardware and software. 

You can get it for free or pay for extra features. And don’t worry, the report won’t reveal any personal information. 

Once you’re done, just copy and paste the full report using the Additional Text Icon.

Lastly - should you decide to use and post the Report now or at a later time, we are willing to have a very close look and offer some insights 

The "RTCReporting_messageLog" file found on Apple devices, such as iPhones and iPads, is a log file related to Real-time Communication (RTC) activity, specifically audio and video calls. It collects data about calls made or received, their type (FaceTime, Messages video), duration, and quality. This file is primarily used by Apple for internal analytics and diagnostic purposes. 

Here's a more detailed explanation:

• What is RTC?
• RTC refers to Apple's technology for facilitating real-time audio and video communication, including FaceTime, video messages in the Messages app, and third-party apps using Apple's call protocols. 
• What does the log file contain?
• The RTCReporting_messageLog collects data about the RTC activity on your device, such as when a call was made or received, the type of call (e.g., FaceTime audio, Messages video), the duration of the call, and the call quality. 
• Why is it there?
• Apple uses this data for internal analytics to improve their services and for diagnostic purposes when troubleshooting issues with RTC functionality.Can you see it?
• If you are a normal user, you won't be able to see the contents of this log file or interpret it directly. It's intended for Apple and authorized service centers to use for diagnosis. 
• Where is it located?
• The file is typically located in the /private/var/root/Logsdirectory on Apple devices. 

Aside from what has already been suggested

Once CleanMyMac aka " BrickMyMac " has been installed and used on the computer

There is no telling exactly what damages this software may has done

One school of thought has already been suggested - remove it as per Developers instaructions

Personally, would add one more step after the removal

Restart the computer in Recovery Mode and choose to Reinstall the Operating System

This may or may not replace elements of the  Home Folder ( User Account )  and replace any corrupted or removed elements and make things right.

The Other school of thought

Start Over from Scratch 

Heavy Handed - Yes ?

Effective - Yes 

For Apple Silicon computer >> Use Disk Utility to erase a Mac with Apple silicon

If going this route - I suggest Not using Startup Assist to migrate everything back.

This will probably Re-Introduce ( CleanMyMac ) back into the Operating System 

CleanMyMac , aka “ BrickMyMac “

New macOS Malware "Cthulhu Stealer" Targets Apple Users' Data

Un-Like Microsoft Windows, which does have “ Disk Cleanup “ and “ Defrag “ as part of their Operating System 

Apple does not 

The choices are yours

Uninstall Clean My Mac, free up another 30+ go of disk space, delete these files & restart…

/Library/Application Support/Microsoft/MAU2.0/Microsoft AutoUpdate.app/Contents/Library/LaunchDaemons/com.microsoft.autoupdate.helper.plist

Outstanding explanation 👍