Specific channel selected will only get 20mhz bandwidth.

[SoulGI]

Device Information:
OS: MIUI 13.0.5 Android 12
Device: Redmi K30 5G
Software Version: 2.19.1

Problem:
When I tried to start hotspot in VPNHotspot with specific channel selected, seems i can only get 20mhz bandwidth. I don't know why. Is it a bug, or a feature?

Example:

1. When I set 36 as the channel for Wi-Fi hotspot, then start hotspot in this software, I can only get 20mhz bandwidth.

2. But when I restored the setting to default, then start hotspot in this software, I can get 80mhz bandwidth. (80mhz is my device max supported bandwidth because it was released in 2020)