Linux Hint published a tutorial about installing Firefox on Raspberry Pi OS.
Install Firefox on Raspberry Pi OS
Chromium is the default web browser of Raspberry Pi OS. Chromium performs really well on the Raspberry Pi. But many people like the Firefox web browser. Firefox is not installed by default on Raspberry Pi OS. But it is available in the official package repository of Raspberry Pi OS. In this article, how to install Firefox on Raspberry Pi OS is explained.
Install Firefox on Raspberry Pi OS – Linux Hint