Many websites offering "free 3DS BIOS download" are actually distributing or outdated bootrom dumps. Worse, some of these sites bundle malware, adware, or fake "download accelerators."
This is why you see so many searches for "Nintendo 3DS BIOS file download." Nintendo 3ds Bios File Download
These files are proprietary code owned by Nintendo. Distributing them is considered copyright infringement. Many websites offering "free 3DS BIOS download" are
Would you like more information on 3DS homebrew or custom firmware? some of these sites bundle malware