Hello.
The conflict you've met is largely due to how the browser handles keyboard scan codes under the Linux compositor before passing them to the AVD gateway. And you should also ensure the IME toggle is disabled, as this feature is optimized for CJK characters and could potentially causing the conflict.
Have you try to open the Windows App web client settings via the gear icon before connecting and manually select the Portuguese (Brazilian ABNT) keyboard layout instead of the default detection yet? Once inside the VM, confirm that the language bar is explicitly set to Portuguese (Brazilian ABNT) and that the Windows session isn't defaulting back to US English.
If you find my answer useful, please mark it as the "Accepted Answer" so other members can find the solution easily. Your help in supporting the community is much appreciated!
Best regards,
Scott Nguyen