Thats not really how estimates work. The actual metering data is ingested in near real time. The metering * pricing plan is processed within a few hours; thats what youre seeing for “estimated spend” IIRC. The actual billing accumulation is done later, at the end of the cycle, because pricing has cross service discounts, price tranches, credits tied to total spend, etc.

“Rolling back” estimated bills is reprocessing the historic metering data by an older or newer pricing plan version. As i mentioned in another comment someone will have messed up a metering type vale (eg GB/B). Thats why theyll need a few hours to redrive the metering data.