Bid strategy
The rule the platform follows when deciding how much to bid in each auction, ranging from manual amounts to fully automated targets.
What makes it wrong.
The mechanism, not the warning.
A target that is far from what the account currently achieves does not produce that result, it produces low delivery. The platform declines auctions it cannot win at the stated price, and the campaign quietly stops spending.
In detail.
Automated strategies optimise toward a stated goal, a target cost per action or return, and need conversion volume to learn. Below that volume they behave erratically, which is usually blamed on the strategy rather than on the signal feeding it.
Changing strategy resets learning, which is why comparing the week before and the week after a change measures the transition rather than the strategy.