I've seen this on several occasions. This one happened to be a jpg file given to us for print. I suspect they had gotten it from a pdf somewhere. I've imported pdf's that have this and the characters would not actually be 3 seperate ones but rather one character as editable text. Files that I personally send as pdf's are not like this as I always convert the fonts. Could this be an adobe thing or...?
Have a look here....
www.youtube.com/watch
If "standard ligatures" are enabled in CorelDRAW, then typing "office" in Arial results in a specific ligature for "ffi" for me.
You can change it back and forth by selecting the involved characters, then using interactive OpenType capabilities.
Like Eskimo said standard ligature, however be careful about changing it as there are those who use them that want them. If you change they'll see it as a typo.
yes, it's an standard ligature of the font, but you can enable or disable it on the Text docker