Hi,
We noticed some unusual activity on your account, so it has been disabled to protect your personal and financial info.
For your security, please confirm your account to let us know it's you.
This is a standard process and should only take a few minutes. Once you confirm your account, your access will be restored.
Thanks,
The Facebook Team
And then this verifcation:
We noticed some unusual activity on your account, so we temporarily disabled it to protect your personal and financial info. For your security, please verify the payment method linked to this account to let us know it's you.
To verify your payment info, Facebook will place a temporary authorization of $1.00 USD with a corresponding code on the card below. Once you start the authorization process, a line item for this amount should be visible on your online credit card statement.