Thanos compact weird storage usage

[Migueljfs]

Hello,

I have thanos-compact running with downsampling and retention period of 2 years (it's still way off, I have this for 1 month only).

I'm running thanos in a cluster and I'm using pvc as storage for thanos compact and this is what I see:

Is this normal behaviour for thanos compact? I have no idea whether it's normal to drop off from ~195gb to ~600mb on a cyclical pattern it seems