My desktop PC was recently infected with a virus calling itself RAV antivirus and RAV VPN. Bit-defender didn't detect it even after I ran a boot scan. I'm pretty sure it was a virus because I could not remove it from my Windows 11 PC. It would let me go through the removal exercise but the RAV would come right back. I luckily got some advice from reddit and used Revo uninstaller. I know RAV is a legit program but the one I got wasn't. I didn't download it. Why didn't Bit Defender catch it ?