What you see is an fi ligature (U+FB01). This is a deliberate feature of the font.
There are some letters pairs which tend to get too close to each other or even overlap. Increasing kerning will make them look too far apart. Ligatures are two (or more) letters combined into one glyph. They are used to make the typesetting look nicer and more professional.
If you want to avoid ligatures there is no need to change the font! Instead simply change the settings in your layout application.
For example, in InDesign you can turn ligatures on and off under the Basic Character Formats in the Paragraph Style.