Recently ran into an issue that I thought was brown out related.
Turns out, it was on the models I had messed with the throws on.
If I altered the limits to 125% (max) and did something like punch throttle, plus full aileron, rudder, and elevator, it acts like about a 2 second brown out. This is probably causing some kind of radio error in the firmware and may depend on your subtrim settings.
It is the first setback I have experienced with the 9XR and I still love these radios.
The problem came up on my Inverza and Yak 54. No crash or damage, but I was boosting the throws all I could on those models. This issue went away when I set the throw back to 100%.
Have you simulated the problem on the ground? It could very conceivably actually be a brown out caused by voltage drop to the Rx when you move all the servos to their limits simultaneously.
Also check carefully that you aren’t stalling the servos due to the over travel. This is quite easy to spot, just make sure that the servo keeps moving freely with stick input and it doesn’t lock out before the stick reaches full travel. This is something to watch for when you start driving servos over 100% throw, especially with digitals because they pull very high current when stalled and will quickly bring down your BEC.