How long ago was this computer upGraded to Ventura ?
Depending on the answer to above and predicated on the Image supplied as accurate there is certainly a lot of Re-Indexing required before an accurate System Data can be produced.
As for Getting Rid of this - read below from Apple
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.
