Running out of storage - system data is huge after upgrade to macOS Tahoe 26.2

Run the third party app EtreCheck and post the complete report here so we can examine it for clues.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

FYI, deleting the cache files is not going to help since they will be rebuilt as soon as you use the associated app. Any increase is just temporary.

if you have Time Machine enabled for automatic backups, it is preparing to make a new backup, including any changes induced by your upgrade.

If you have not connected your external drive recently, snapshots of the lists of files to be backed up are being saved on the boot drive.

if this is the case for you, connect your external Time Machine drive and let it make a "real" backup to the external drive, and it will clear those snapshots when competed.

Reducing System/Volume/Data is a common question. 

1 -  System data taking too much in MacOS Sono… - Apple Community

2 - Time Machine Local Snapshot won't delete - Apple Community

3 - Over 60% storage blocked by System Data - Apple Community

How to free up ‘System Data’ and other storage on your Mac from a fellow colleague  @ neuroanatomist

Use another application to see where space is being used  Storeograph  on the Apple Apps Store 

View APFS snapshots in Disk Utility on Mac

Suggest getting an External SSD Drive and start moving your Pictures, Videos, Music and any other large files you have control over, OFF the Internal drive and Onto the External

Understanding iCloud Drive from a well written User Tip from @ Richard.Taylor

There are  two effective ways to remedy this issue:

1. Quick Fix Actions:

 For Apple Silicon computers, use Disk Utility to erase a Mac.

Always make a Time Machine backup before proceeding.

 Migrate only the user account, not the entire system.

 Reinstall only the necessary applications from the Apple App Store or directly from the developers.

2 - Generally

When the user discovers this issue, in this specific case, computer’s internal drive capacity is small, such 256 GB

Unfortunately, the user’s storage needs may have increased since the computer was purchased.

To future-proof the computer, consider spending extra money upfront on a larger drive capacity and adding more unified RAM.

Note - On Apple Silicon and newer computers. The SSD Drive and the Unified RAM are Soldered to the Logicboard and can not be upgraded.

Review this for some help:

https://discussions.apple.com/thread/256239409?sortBy=newest_first

tbirdvet wrote:

Review this for some help:

https://discussions.apple.com/thread/256239409?sortBy=newest_first

👍

🦉-53

<<. etrecheck report >>

Your 256 GB drive is very small by todays standards. You may need to consider always using an external drive as well.

you need not use a huge spinning magnetic desktop-style drive with its own power supply. Here are some examples of smaller drives for laptops:

VPN:

A virtual private network, or VPN, is a private connection over the Internet from a device to a specific network.  VPN technology is widely used in corporate environments. If you need to be "present" on an institutional network, a VPN is a great tool for accomplishing this. It is generally issued and controlled by the institution.

Almost all other uses are a SCAM. There is generally no need for you to have a private (and almost always MUCH slower) connection to a VPN vendor's Network, except to make it easier for them to harvest your data to sell. If you are behind a Router you control or Trust, there is NO security advantage whatsoever in using a VPN. Your connections are already encrypted in most cases.

If VPN vendors just stopped there, it would be bad. But many of these packages also insist on scanning all your files, non-stop, -- nominally looking for viruses, but who knows for sure what data they are harvesting. Their non-stop file reading punishes your computer's performance in the process.

Some also break into your other secure connections so they can be FIRST to examine your data, often leaving your Mac MORE vulnerable to attack.

What VPN service to use?

DON'T use VPN services

https://gist.github.com/joepie91/5a9909939e6ce7d09e29