I’ve been seeing this issue with Keepa on several listings recently.
Here’s an example of a product with no variations. The timeframe is the last 30 days. Keepa’s data tab shows 50 drops but is really more like 5 or 6 according to the graph.
I think Keepa is now counting the BSR movement down when another product’s BSR in the same category moves above it as a drop.
Looking at that chart and by eye I can see a lot more than 5 or 6 drops. Not all drops are large and some won’t be visible on the chart. You probably have 20+ drops on that chart before the big drop. I’d be very surprised if the drop count is not accurate.
Then it could be an issue with how Amazon is reporting BSR or how Keepa is collecting. The drop count does look accurate but if the BSR points recorded are dropping when they shouldn’t be then you’ll need to read the chart differently and apply some sort of smoothing so only more significant drops are counted. If you send the ASIN I’ll see if anything jumps out.