I found a bug when using p-inputNumber with maxFractionalDigits and a suffix. It only allows you to type one number after the decimal point and then it wipes away the suffix. There is no way to type a number with more than 1 digit after the decimal point.
Try the Stackblitz from https://primefaces.org/primeng/showcase/#/inputnumber in the example for Min-Max Fraction Digits. Add a suffix= to the example and you'll be able to replicate the behavior