What is it?
Borrow APY is the current annualized rate borrowers pay on variable debt. It is also a live snapshot. Ronnie shows the variable rate from Aave's reserve data.
Why does it matter?
When this jumps, new borrows get expensive and existing variable debt accrues faster. That can push Health Factors down slowly even without a price crash.
Example
ETH borrow APY rising from 2% to 6% means ETH borrowers are paying more. Look at utilization on that reserve to see if the pool is crowded.
Where can I find it?
Asset detail Variable borrow APY. Markets Borrow APY column (USD-weighted). Cross-Chain borrow APY column.