It is true that in this “Serbo-Croatian”, or how it’s modernly referred to as “BCSM” speaking region, the letters “Č” and “Ć” are pronounced in different ways.

In Serbia, for example, the difference between them is the clearest, however in many other areas, the difference between these two phonemes is much smaller.

In Serbia, “Č” is “retroflex”, and “Ć” is “alveolo-palatal” – and also, this is the standard pronunciation of these two letters in the entire “BCSM” region. It’s pronounced this way in Montenegro and parts of Bosnia and Croatia as well.

However, many speakers (especially the ones from Croatia and Bosnia) pronounce these two letters equally – a phoneme which is between these two – a “palato-alveolar affricate”. That’s where the confusion comes from.

Same thing also happens with it’s voiced counterparts: “Dž” and “Đ” :)