crucial x9 2tb capacity freeze

so I realised that my SSD has been telling me there's 1.55tb space available for weeks, if not months now - what is going on? there's also like 400gb of something called 'purgeable data', and I can add and access all the files alright, but clearly it's not updating the volume used/left - I'm sure I added another 10gb of photos this past week alone. I'm on Mac OS 15.7.