Hi Chama9714,
Thank for posting your question in Apple Support Communities. We see that a lot of the storage on your Mac is being used by System Data.
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. You can manage your data that falls
outside the other categories using Finder or the 3rd party apps that created it.
More details here: See used and available storage space on your Mac
We suggest checking out the section, "Free up storage space in other ways" in this resource: Free up storage space on your Mac
Let us know if this helps.
Take care!