1. Tightening target ROAS
ROAS goes up, volume collapses. The ratio improved; the profit did not.
2. Narrowing targeting
Conversion rate rises because you removed the people least likely to buy — along with some who would have.
3. Cutting "expensive" keywords
Expensive per click is not expensive per order. Cutting on CPC alone routinely removes the best terms in the account.
4. Adding brand budget
Blended numbers improve instantly. Total revenue does not move, because those people were already coming.
5. Pausing everything unprofitable at once
Feels decisive, removes the volume the bidding was learning from, and puts the account back into learning at the same time.