The letter combination fl does not space in Inkscape. I've set the letter spacing to 30 in the pictured case, and as can be seen the fl in flying is not spacing out. Is this a bug?
This is a guess: fl is a ligature, a special character which contains f and l together.Many fonts have them. I do not try to guess the exact method how you did pick it.
Here's a part of Arial's special characters, in the beginning of the list there's fi and fl
Advanced typesetting software can place ligatures automatically for nice looks instead of separate letters if that's specified in settings, but they also can take them off if there's a forced letter spacing. Inkscape isn't such program although very useful for many purposes.