Cold-Start Ads and the Feedback Loop

An advertiser launches 500 new creatives on Monday. By Wednesday only 30 of them have received meaningful traffic; the rest have < 100 impressions each and near-zero pCTR. The advertiser argues the system never gave the others a chance.

1. Explain the feedback loop mechanism that produced this outcome.
2. Design an exploration strategy that gives new ads a fair chance while bounding revenue loss; include a rough number for the exploration budget and how you would set it.
3. What non-exploration levers reduce the cold-start problem in the first place?