Submitted by cmichel
https://github.com/code-423n4/2022-02-anchor/blob/7af353e3234837979a19ddc8093dc9ad3c63ab6b/contracts%2Fmoney-market-contracts%2Fcontracts%2Fmarket%2Fsrc%2Fborrow.rs#L304
The borrow rate uses a simple interest formula to compute the accrued debt, instead of a compounding formula.
This means the actual borrow rate and interest for suppliers depend on how often updates are made.
This difference should be negligible in highly active markets, but it could lead to a lower borrow rate in low-activity markets, leading to suppliers losing out on interest.
Ensure that the markets are accrued regularly, or switch to a compound interest formula (which has a higher computational cost due to exponentiation, but can be approximated, see Aave).
Alex the Entreprenerd (triage) commented:
