Lemmy isn't letting me post images anymore

Whenever I try to upload an image to Lemmy I get this error: data":{"msg":"Couln't upload file, Error in DB, IO error: Os { code: 28, kind: StorageFull, message: No space left on device }","files":null},"state":"suc

I figured that this meant my phone's storage is full, but I checked it and it wasn't. Is there something I can do to fix this?