Hi,
the control loop does not provide individual adjustment.
Since it's rate control, as long as the control loop can still control the rate (requested rotation rate, agility), it will equalize automatically.
At least that's what I think I notice myself.
But if you max out, it could be that on axis is already at the physical/aerodynamical limit, while the other still has headroom, means you have like an oversteer or understeer, depending on what axle lets go first, front or rear.
I would try and reduce agility a bit, see if it becomes more symmetric.
But that of course depends on where we're coming from, and here I have not enough information from you yet ^^
Another thing could be, your stick calibration is off, so you don't reach 100 % on all axis. Easy enough to check
Cheers
Eddi
Born to fly ...
forced to work.