The audio forwarding volume is weak and the phone still sounds.

- [x] I have read the [FAQ](https://github.com/Genymobile/scrcpy/blob/master/FAQ.md).
- [x] I have searched in existing [issues](https://github.com/Genymobile/scrcpy/issues). #4133

**Environment**
- OS: Windows10
- scrcpy version: 2.1
- installation method: Windows release
- device model: Hisense HLTE556N
- Android version: 11

**Describe the bug**

The phone was turned up loud enough for me to hear it on the computer , I was going deaf.😂
There are no errors in the command line.
```
scrcpy 2.1
D:\soft\scrcpy-win64-v2.1\scrcpy-server: 1 file pushed, 0 skipped. 92.8 MB/s (56955 bytes in 0.001s)
[server] INFO: Device: [Hisense] Hisense HLTE556N (Android 11)
INFO: Renderer: direct3d
INFO: Texture: 824x1648
```
thank you!

Start by reproducing the reported command on Windows 10 with Android 11, using the Hisense HLTE556N details and scrcpy 2.1 environment. Compare the forwarded audio volume with the phone's speaker output and determine whether the phone audio is muted; done means computer playback is usable without the phone continuing to sound.

Written by the indexing model from the issue text.