If anyone's consumed any media set in a medieval setting (whether it be fantasy or not), there's going to be a good chance that the leather armour is worn as the novel's 'light armour' for the characters. Which just boggles my mind. While leather armour was used and is effective as 'light armour' in protecting it's wearer, it's effectiveness was matched or exceeded by 'padded armour'. And not only that, but padded armour was also cheaper and easier to make than leather armour, making them far more cost-efficient as well.
Because of that, padded armour was historically more prevalent than leather armour ever was but for whatever reason, fictional media just tends to favour leather armour over padded armour.
For those that don't know what padded armour is, it's essentially several layers of linen and wool sewed together (think a super thick medieval jumper). And contrary to what that description would have you believe, padded armour was indeed very effective in protecting its wearer and since it's cloth (meaning it didn't have the limitations of stiff leather) it can more readily and easily be designed to cover more of its wearer's body. For a quick example of how effective padded armour can be, it can absorb a direct blow from any sword (excluding greatswords) and the wearer wouldn't even be scratched. Moreover, padded armour can be easily repaired by being sewn together again, something not possible with leather armour.
That's just a quick rundown on why padded armour is objectively better than leather armour and why it irks me so much that the poster boy for medieval light armour is leather armour and not padded armour. Ultimately, it's the author's choice as to how they depict the armour worn by their characters, I'm just wanted to express that leather (objectively) isn't the best form of light armour, let alone the only one.