System Data Files Huge and Keep Growing

1 - Launch Disk Utility and select the Mac-Data drive.

2 - go to the View menu and select Show Local Snapshots.

3 - you can select a local snapshot and use the "-" button at the bottom to delete it. Leave one or two. That will save you some space but additional snapshots will be recreated.

When you delete a snapshot you probably won't regain the entire displayed size as it uses lots of hard links.

As the Users issue is focused solely on Drive Space, will narrow and focus only on that specific aspect.

It has been years since seeing and using TechTools Pro and not even sure if it is supposed on Monterey.

Back in the day when I used this software ( OS X 10.4 Tiger ) , it would create a Separate Partition ( Virtual or Real ) on the drive in-order to work its’ magic.

If that is still the method, there is space being used. The user will need to investigate all the details regarding this software to determine just how it works and if it is supported on Monterey.

Time Machine Backup is not or configured .

But yet there are list 19 Snap Shots listed ( Space Used ). These , I suspect they are coming from Carbon Copy Cloner which should have moved them to the External Drive once the Cloning process has been completed

Would suggest two things. Make sure one is using the current version os CC 6.1.1 and read up from https://bombich.com/kb/ccc6/frequently-asked-questions-about-carbon-copy-cloner-safetynet#safetynet_dont_delete regarding the SafetyNet Aspect of the software. This may account for Space On the Internal Drive being used. Once that specific aspect is resolve, one may or may not find Space Used will be reduces.

Description: 

Q - iMac (Retina 5K, 27-inch, 2019), 3.6 GHz 8-Core Intel Core i9 with a 3 TB fusion drive. 

Q - 1 TB Windows partition and a 2 TB macOS partition running Monterey version 12.3.1.

Hardware Information:

iMac (Retina 5K, 27-inch, 2019)

Drives:

Q - disk0 - APPLE SSD SM0128L 121.33 GB (Solid State - TRIM: Yes) 

Q - disk1 - APPLE HDD ST3000DM001 3.00 TB (Mechanical - 7200 RPM) 

Kernel Extensions:

Q - /Applications/TechTool Pro 15.app    [Not Loaded] spdKernel.kext - com.micromat.driver.spdKernel (1.0 - SDK 10.14)

3rd Party Preference Panes:

Q - TechTool Protection (Micromat, Inc. - installed 2022-04-26)

Backup:

Time Machine Not Configured!

Q - 19 other local snapshots

Q - 3rd party backup: Carbon Copy Cloner

Q -  2022-04-28 21:01:17 TechToolProDaemon Crash (2 times)

    Executable: /Library/PreferencePanes/TechTool Protection.prefPane/Contents/PlugIns/TechToolProDaemon.app

To see all aspect in the Hardware and Software installed on the computer >>

Suggest downloading the Application Etrecheck directly from a well Respected ASC Contributor. And Safe to use.

The application is free or paid from added features. 

Run the application with Full Disc Access ( Security & Privacy - Full Disc Access ).

It will take a Snap Shot -  both the hardware and software.

 The Report will Not Reveal Any Personal Information. 

Post back the Full Report - copy and paste - using the Additional Text Icon ( 3rd Icon to last )

We can have a look at the report for possible issues and may have possible suggestions to resolve the issues.

Hi, ScorpioX3.

I am William, and I am here to solve a problem.

First, update your Mac to the latest Monterey version. An update is kind of a rewind for the computer to clear out any unnecessary cache.

If that doesn't work, check if other users have been using the Mac as well. Commonly System Data will fluctuate, so it's just a matter of time.

Finally, if that STILL does not work, store all important files on to an external hard drive and restore your Mac computer. This will wipe out all data. Do note that if you wipe all data, other users' data will be wiped too.

Hope this helps!

Sincerely,

William :)

EDITED

The Drive has a finite Capacity. Once needs to Off Load some of the e-Mails, Pictures, Messages, etc as per your photo above.

Add is the iCloud Storage. Whatever is on iCloud is also stored Locally on the Internal Drive. That is how iCloud works. iCold is not like an External Drive and used for Storage. It is a conduit to have changes to a file to be uploaded to iCloud and the changes are reflected to all other devices the user owns and using the Same Apple ID.

What is “Other” storage on a Mac, and how can I clean it out?

Free up storage space on your Mac

OmniDiskSweeper Safe to use

GrandPerspective 

How to delete Time Machine snapshots on your Mac

See used and available storage space on your Mac

Locate backups of your iPhone, iPad, and iPod touch

The final word from Apple on Managing the " Other " Category

Other: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

Hey, ScorpioX3.

Once you delete an app, especially a game, your Mac sometimes only deletes the game data and app size, but not all the cache stored when you are playing the game. So your Mac does not know how to deal with all the remains of the cache. You can see my solutions above this post.

Advise and suggestion offered were in the best interests of the computer, done on a volunteer basis and in good faith.

IMHO - there has been enough solid and reliable information provided for the User ( you ) to make an informed choice as to what course of action is required to remedy this computer situation.

A Fast and general view of the Report supplied.

Will look in Great details tomorrow when I am free.

Right away I see a Fusion Drive and right here this will be a Performance Bottleneck even with a 7200 RPM Mechanical Drive

Secondly, running with a Great Many System Modifications . This type of setup plus running Several Different versions macOS plus a Bootcamp - is a potential mix for issues

As mentioned - when free tomorrow will go through with fine-tooth comb and et back to you

You are welcome

Do come back to the Apple Support Communities ( ASC )  in the future, if / or when additional questions may arise