On Prime Day, AI shopping referrals out-converted search, email and social for the first time, a shift that threatens Amazon's grip on discovery.

Retail experts attribute the 9.3% year-over-year increase in spending to high inflation and shoppers purchasing more discretionary, long-lasting products.

The multibillion-dollar spend marks a 9.3 percent year-over-year increase that retail experts attribute to high inflation coupled with shoppers' purchasing of more discretionary,…