Time Machine share larger than original size

I have a Drobo 5N. I created a separate Time Machine share for my backups. I put a threshold on it of 1TB. However, it seems to be larger than 1TB. I reviewed this article which I found from a different post, but I don’t have a Volumes tab with my Drobo Dashboard.

Does anyone know if I’m missing something? It appears that the threshold is being ignored.