huge storage vs. Disk utility difference

hey guys, having a problem and searching for solutions here. Photoshop had a problem saying volume storage full, while in settings > general it seems empty but the disk utility claiming its full, having 687GB of purgeable space. Not an native IT guy nor a macos expert, but work with apple/ macos since 10+years in creative field. macos 15.1 (24B83) 1.) What's the actual right info? Full or empty? and 2) how to remove the purgeable space?