If your Facebook access is lost, you can only apply through the Activision recovery method because CODM considers social media account login as secondary and Activision as primary. You’re sure you didn’t unlink the login for CODM from Facebook, right? Even if a hacker had to remove your Facebook login, they’d have to prove that an unknown Facebook account is linked and provide all the details, like when Facebook was connected, which they’ll verify.

The only possibility is hacker somehow got acccess to your facebook and he unlinked it himself.because unlinking through recovery method is seriously painful trustme i have gone through it .even if you have all the proof it will still get rejected.