Why does Blink have a Lightning - onchain imbalance threshold?

Blink has implemented a Lightning/on-chain imbalance threshold in a rolling window to help keep fees low for small transactions with low monthly volume.

The imbalance between Lightning and on-chain transactions can impact the liquidity of Blink and result in increased costs. By setting this threshold, we can ensure that our network remains efficient and cost-effective for all users. See the Blink App for your current threshold and any applicable surcharges.