Si tu veux plus de détails, c'est expliqué dans la doc officielle : https://www.expresslrs.org/software/switch-config/#why-do-you-keep-saying-put-arm-on-aux1
Why do you keep saying "put arm on AUX1"?
For safety and performance reasons.
SAFETY
AUX1 is sent with every packet going out, this is the most reliable way to be able to tell your model to disarm. If your arm switch is on another aux channel, it may be several packets before that switch is transmitted, and there's no guarantee that the RX will actually receive that packet. There's a non-trivial chance your model may not ever disarm if the link quality is low and it just so happens that the packet containing the arm switch is getting missed every time. Forcing the arm switch into every packet on AUX1 means that if any packet is received by ExpressLRS, it will disarm your model, not just a less than 1-in-7 chance.
It also protects against unintentional disarms caused by a corrupt packet changing the value of the arm switch to disarmed. Betaflight requires that 4x "disarm" commands are received before disarming to guard against this possibility. With arm on AUX1, a single corrupt packet can not disarm your model. With arm on AUX2-8, the one corrupt switch value will be sent 6 times before the value is refreshed, but the flight controller would have already disarmed by that point.
Your transmitter and receiver also act differently when “armed” and when “disarmed”. When disarmed, the transmitter and receiver are free to adjust their communication in order to make the LUA and other configuration operations more responsive. When "disarmed", everything will appear to be working appropriately but none of the safeguards will be in place and performance will not be what you expect.
When IsArmed is enabled, these safeguards are applied:
All "Button" inputs are disabled
All "Joystick" (5-way buttons) are disabled
Bump to Share is disabled
VTX Admin is disabled
Integrated VTX channel change is disabled
PERFORMANCE
When IsArmed is enabled, these performance features are activated:
Dynamic Power is fully enabled
Race telemetry mode turns telemetry off
Some thermal-based fan controls are enabled
Arming is an extremely important part of the performance of the control link. Please use Aux 1 / Chan 5 as indicated. Also keep in mind that for ExpressLRS, ~1000us is the disarmed state and ~2000us is the armed state.