System Data Using 360GB on MacBook Pro (M3 Max, 2023) — How Do I Fix This?

I'm running into a serious storage issue on my 16-inch MacBook Pro (Apple M3 Max, 36GB RAM, Nov 2023). I’m on macOS Tahoe 26.0.1, and my System Data has grown to over 360GB. That doesn’t seem normal at all, and it’s now limiting my ability to work.

About my setup:

• Not using iCloud Drive
• Desktop/Documents/Downloads synced with Dropbox
• No Time Machine backups stored locally
• Parallels installed but never used
• I do photography and video editing, but I’ve already cleared cache from Lightroom, Photoshop, Premiere, and After Affects
• I also use Topaz Photo and Gigapixel, DXO 9, On1
• I use RadarOmega and RadarScope for torm tracking

I’ve also checked ~/Library and /Library folders for large logs, caches, and Application bloat. Nothing obvious explains such a massive System Data size.

Questions:

1. Why would System Data take over 360GB?
2. Is there a safe way to identify what this storage actually is?
3. Any way to clear it without doing a complete wipe and reinstall?
4. Are there known storage bugs with macOS Tahoe?

If anyone has terminal commands, cleanup strategies, or troubleshooting steps, I’d be grateful. I do not want to use third-party apps like CleanMyMac. This feels like a runaway cache, but I cannot find where.

I can provide an EtreCheck report if needed.

Thanks in advance for any help —