When I go to the link I provided, it shows me the following build : 2025-03-27_10-47_v4.0-rel_2aa96eb60

So I guess what I am downloading is the firmware v4. Unless I am on the wrong regional version. How can I know if it is the Chinese or Intl version ?
Pushing the encrypted update to /sdcard/ and triggering the update does not work. I don't know why but I guess it is the same reason as why it does not work either with OTA.
I will try with stock recovery + adb sideload.
I have not seen custom recoveries for Onyx yet. Do you recommend it for NoteAir3 ? If yes, which one ?