Creative fatigue shows up before the ROAS does
Hook rate and hold rate fall before cost per purchase rises. Hook rate is 3-second views divided by impressions, typically 20% to 30% on a healthy video. When it drops by a third against the ad’s own first week, that creative is finished.
Fatigue arrives faster on small audiences and narrow geographies. A UK-only brand spending £500 a day will burn a concept in two to four weeks. Plan the replacement before the decline, because a fresh concept takes 5 to 7 days to exit the learning phase.
Auction costs rise on a calendar you do not control
Meta CPMs move with seasonal demand. Costs climb through Q4 and peak around Black Friday, commonly 20% to 40% above the Q3 baseline in retail categories. A flat budget buys fewer impressions, so order volume falls while the campaign structure looks unchanged.
Compare CPM year on year and month on month before touching anything. If CPM is up 30% and ROAS is down 25%, your buying is holding and the market got more expensive. The fix is margin, creative and a firmer bid cap.
Signal loss is the quiet one
Event match quality in Events Manager should sit around 7 or higher out of 10. A checkout migration, a consent banner change or a stripped-out email parameter drags it down within days, and Meta then optimises on worse data.
Check deduplication between the pixel and the Conversions API. Double counted purchases inflate reported ROAS, then a correction makes performance look like a crash. Confirm the attribution setting has not been switched, because moving to 7-day click only removes view-through orders.