Hello Cidal,
We understand that you're experiencing issues using your microphone on the Quest 3 while accessing the Xbox Cloud app, and we'd be more than happy to see how we can help!
Something you can check is whether the Xbox app's in-game menu includes a three-dot button, which should appear when the app is open. Click "Unmute" to prompt the Quest system to request microphone permissions.
If you still run into problems, please reach out via private message so we can look into this further. Please select our name to get to our profile page, or click here. From there, click "Send a Message" to privately message us! Please remember, you must be signed into the community first to send us a private message. We're eager to hear from you!