Details

In depositCollateral, redeemCollateral, mintDsc and liquidate functions you are using nonReentrant modifier to prevent reentarny but since the only external call is calling a function on ERC20 tokens there is no way to someone be able to re enter the function, even if attacker some how re enter the function nothing will break since you update the state before sending tokens.

nonReentrant modifier update the state two times, by using this modifier in functions they cost a lots of gas, for being more safe you can only use it with liquidate function and remove it from other functions.