I've stumbled upon this issue on every ionic project so I'm logging it here. Ionic buttons have by default wide letter spacing. Mostly this is not what you want. Fix it like this:
ion-button {
text-transform: none; // this prevents all caps
font-size: 14px; // optional
font-family: 'Open Sans', sans-serif; // set your project font to it
letter-spacing: normal; // this fixes wide spacing
font-weight: 600; // optional
}