Kamembert keeps a snapshot from each scan. The next time you scan the same place, the Activity panel shows what is new, what changed, and what is gone since last time. It is an easy way to spot the folder that quietly grew, or to confirm a cleanup actually freed what you expected.
If you want a fixed point to measure against, lock a scan as the baseline and every future run compares to it instead of the most recent one. Snapshots share a size budget, so the oldest unlocked ones are dropped automatically once it is reached.