GNU/Linux Mint 20 Installing Broadcom BCM4331 Driver Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install Broadcom BCM4331 Wi-fi/Bluetooth Driver in Mint 20.x Ulyana/Ulyssa/Uma/Una LTS GNU/Linux.
The Package Provides the Source Code for the wl Kernel Modules and makes use of the DKMS Build Utility to Install them for the Running Kernel.
GNU/Linux Mint 20 Broadcom BCM4331 Driver Installation Guide