fix(rate_model): increase MAX jump rate and full rate #1233
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Recently all USDT on Polkadot was borrowed, leading to Moonwell USDT borrow rates of 192% and Interlay $492k of USDT max borrowed, resulting in Interlay USDT borrow rate pegged at 45-50%. The negative thing was that there was no remaining USDT lending liquidity for lenders to withdraw their capital.
Interlay referenda 96 was approved to adjust the USDT/USDC lending params to set the jump rate to 20% and the full rate to 150% with optimal utilization of 80%. After community and team discussion, this solution was agreed to use the higher full rate to push lending back down towards the optimal lending utilization.
https://interlay.subsquare.io/democracy/referenda/96
Unfortunately the referenda failed to execute because the 150% proposed full rate exceeded the hard-coded max value of 50% for the full rate.
https://interlay.subscan.io/block/4905046?tab=event&event=4905046-0
In this commit I recommend:
I definitely support having limits since people might submit a value with wrong number of zeros accidentally. But let's place the limits higher than any "reasonable" value that we might set in governance. I can see us potentially having a market with jump rate 50% and full rate 300%.