-The bug-

On controller and kbm (keyboard and mouse), you can sprint and then hold the jump button to sprint jump perfectly. On touch, however, if you sprint and then hold the jump button you get one jump but no more (you don't even have to retap the sprint button though, as holding jump keeps you sprinting implying that the dev team intended for touch players to be able to sprint jump). 

-What this affects-

This means that touch players will always be slower than their controller and kbm counterparts, as they need to time their sprint jumps and that allows for human error. This is especially important in pvp situations where either you need to chase fast or you need to get away fast, as it gives touch players a massive disadvantage in these situations.

-A fix-

A simple fix would be making it so that when mobile players sprint and then hold the jump button they continue to sprint jump just like how it works on other platforms.