Problems with plant operations can be remediated and they seem...

Problems with plant operations can be remediated and they seem to have spent a lot of money doing that recently. My main concern with OBM is the grades being mined. With a short 4 to 5 year mine life, mining and processing ore in the first year that was 60% of the DFS grade has been a significant impediment. Assuming that the resource estimates are reasonable then the only way to reconcile the DFS grades with the current experience is to have above DFS grades in the remainder of the ore bodies. The weighted average DFS grade for the three sites mined is 2.60 g/t, the observed average grade to Sep 2021 was 1.56 g/t. Does anybody know whether this is a likely/common experience (i.e. lower grades then higher grades as mining progresses) generally or better still for the ore bodies being mined?