Apple has just released macOS Mojave 10.14.6 Supplemental Update, which it says addresses problems in some Macs when waking from sleep. This is slightly less than 1 GB in size.
Although the release refers to security notes, none are yet available. When they are, I’ll post a link to them here.
A standalone installer for this update is now available here.
This update doesn’t bring an EFI firmware update for T2 models, at least, but brings the build number of macOS up very slightly, from Version 10.14.6 (Build 18G84) to Version 10.14.6 (Build 18G87). However, there are EFI firmware updates for some MacBook Pro models, as detailed here.
There are no changes at all in bundled applications, nor in the many frameworks, bundles etc. in /System/Library.
(Updated 1745 UTC 2 August with firmware update link.)