I probably did do the Security update, can't 100% recall but I do remember that my 2011 Core i7 MBP had a Security Update that upgraded its bootrom from 85.0.0.0.0 to 87.0.0.0.0.The "supplemental" updates to 10.14.6 were included in the full installer, but security update 2019-001 for Mojave is not included. Software update should be telling you that update, as well as Safari 13.0.3, is still required.
Did the Safari Safari 13.0.2 and 13.0.3 updates.
App Store Vers. 3.0 ( (1003.3) ) no longer shows a history of installed system updates. Thanks Apple..