So we analyzed
the niche and the recent changes in the campaign manager, and find no reasons that might've influenced the deterioration of metrics.
Also seasonality couldn't be the reason, because the niche is in the middle of the high sales season. The only parameter that has changed - the rating, which fell by 0.2 points.
ACoS increased from 33% to 55%, while the conversion rate decreased.
Then we analyzed the listing and noticed a new negative review.
Immediately contacted the buyer, and we were fortunate to agree that he would remove the review.