If a user types hUNTER2 and your service corrects it to Hunter2, have you reduced security? How much will it help?
This fun paper explores this Q, finding you can preserve security and fix 10% of logins:
pASSWORD tYPOS and How to Correct Them Securely https://www.ieee-security.org/TC/SP2016/papers/0824a799.pdf