Well, here on VC:MP you can use the /setconfig game_sensitivity value and /setconfig game_sensitivity_ratio 0.5 that will fix the Y axis, or in better terms, making the vertical movement half value of the horizontal one, in which was meant to be a legal configuration, but the people is still unable to comprehend because they got a dead peanut brain or a lower IQ than 50, in which they marks it as an illegal modification.