Well an extra payment is an “early payment”. But I understand that some institutions won’t apply an early payment to reduced outstanding Principal.

Fun fact - in Australia they have what they call “Mortgage Offset” accounts. Basically it’s like a savings account, but instead of earning interest it is offset against the outstanding Principal of your mortgage on daily interest calculations. Thereby you “earn”the interest rate of your mortgage. I was very surprised the US doesn’t have these. They’re great because you can almost pay off your mortgage but still pull the funds out instantly if you need them.