The weekly cost average takes the weekly sums in the elements that’ve been current for that financial year (both provisions and charging) and multiplies them by 52 to get the total annual cost.
If you think you’ve seen an anomaly, which we’ve seen happen, it’s not due to the underlying data but to the supporting tables that provide better user experience views. In these cases, we have scripts to regenerate costs from source tables covered in this article Care package cost screen totals not showing correctly
If this is required, please raise a new case online and reference the title of this article with the following:
The Person ID.
Screenshots of the Person weekly cost average, and supporting elements costs from the costing tab.