GNU/Linux Debian Bullseye Installing BrosTrend AC1200 Wifi Adapter Driver Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install BrosTrend AC1200 USB Dongle Wireless Wi-fi/Bluetooth Driver in Debian Bullseye 11.x GNU/Linux.
And the Debian 11 BrosTrend AC1200 Wireless Adapter Driver Setup is based on the Realtek rtl8812BU or rtl8822BU Chipset Driver Installation.
Especially relevant, if you are Unsure about your Wifi Device Chipset then see: How to Get Wireless Adapter Info on GNU/Linux.
GNU/Linux Debian Bullseye BrosTrend AC1200 Wifi Adapter Driver Setup Guide
See: Realtek rtl8812BU/rtl8822BU Linux Driver Installation
Last, in case of Issue you may see: How to Update Linux Firmware!