That refers to Defender Definition update and\or an engine update, Protect doesn't support these updates since their not bulletins or even updates.
Here is the Microsoft article: Microsoft Security Advisory 4022344
Is Microsoft releasing a Security Bulletin to address this vulnerability?
No. Microsoft is releasing this informational security advisory to inform customers that an update to the Microsoft Malware Protection Engine addresses a security vulnerability that was reported to Microsoft.
Typically, no action is required of enterprise administrators or end users to install this update.
Why is no action required to install this update?
In response to a constantly changing threat landscape, Microsoft frequently updates malware definitions and the Microsoft Malware Protection Engine. In order to be effective in helping protect against new and prevalent threats, antimalware software must be kept up to date with these updates in a timely manner.