Cannot go over 26km/h (7m/s) with my Mavic Air

I’ve an old Mavic Air.

My Mavic Air max speed in normal mode is 25-26km/h (7m/s).
In sport mode I can reach 60-62km/h.

I think there is too much difference.
I can use sport mode to travel but I lose gimbal stabilization.

I would like to use DJI Assistant to increase the normal speed to 35-40km/h.
I changed g_config_control_avoid_atti_range without results.

Any hint, please?