MacOS 12.4 bug, Around 100 Go lost after update from 12.3 to 12.4

Understand, we are all working Remotely from all around the world. Therefore, we do not have the On-Hands experience the User ( you ) has with this computer.

Reliable , accurate, details and context will really help to pinpoint a possible solution.

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

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See used and available storage space on your Mac

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The final word from Apple on Managing the " Other/ System Data “ Category

Other / System Data: 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.

Try the suggestion supplied above first and in any order.

This my help to remove some outdated or larger files that you have control over.

Once that has been completed and the Trash has been emptied >>

Rebuild the Spotlight index on your Mac. This procedure can take some time and even a day to two jousting from having a 1 TB Drive and only having 50 GB Empty Space Available.

Notation and very very important - it is suggested to keep at least 15%  to 20% of the Drive Total Capacity as Empty Space for good operations of the computer and for additional updates to Monterey to download, expand and install.

The 20% of 1 TB would translate into 200 GB as Empty Space.

This computer ( based upon supplied information ) is very close to stop booting up at ALL

Give this a try to see if you get a better indication of available space: How to rebuild the Spotlight index on your Mac - Apple Support.

I doubt the update took away 100 GB, but there certainly can be something else going on.

Please provide greater detail: Writing an effective Apple Support Commun… - Apple Community