I guess this has been said before but I want to reiterate it here.
The 3 button navigation is simpler, much faster than gestures and less prone to input errors than gessure navigation.
It’s easier to use the phone one handed when using 3 buttons especially considering the size of phones nowadays.
The only real downside to the 3 button bar is the space it takes away from the screen. I can’t deny you get better immersion due increased screen size and gestures being intuitive (for me at least.
With that said I understand that depending on the brand the feel of gestures and their quality can vary (like between a pixel phone and a xiaomi device), but in terms of efficiency (and maybe slightly improved battery life due to less animations) and simplicity the 3 button navigation is still miles ahead.
What I dislike personally about the 3 onscreen button thing is most phones are oled now and I’d rather not have anything permanent on my screen because of potential burn in but that goes for the status bar as well.