When typing a letter in Word, if the line spacing is on "1" then why is the line spacing coming out double-spaced?

I am typing a letter in Word, and I made the line spacing at 1. However it’s coming out double spaced. I keep going back to the line spacing, to check as I try to figure out why it’s double spaced. I have looked at other icons in the toolbar, to try to figure out if there’s something I’m missing, but the only thing i can see for my issue is “line spacing” and it is definitely got a check mark at 1, not 1.5, not 2.

Please help!