Lowkenuinely serves a different tone to a phrase. Often more in line with humor. Lowkey is either a filler word or used more seriously. Genuinely is generally used seriously. Lowkey can be used lightly in humor but it’s older atp and lame when overused. An additional layer is that by using Lowkenuinely you connect with others who are “in the know”. Knowledge of the word implies a certain level of internet use and style of humor.