microG Services and Companion were "built for an older version of Android"

Describe the bug
The apps from the microG F-Droid repository display a notice saying "This app was built for an older version of Android and cannot be updated automatically".

Is that expected? After searching online for that message, it seems to be due to the app's minimum supported SDK version... or something.

I have to check for updates myself every now and then, and it took me a while to find out that it wasn't updating automatically like the other apps. Maybe it's expected, and maybe I shouldn't be updating everything automatically anyway; but I worry about not having the latest patches.

To Reproduce
Steps to reproduce the behavior:

1. Install LineageOS 23, then install the F-Droid APK from their website.
2. Add the microG F-Droid repository and install the apps microG Services and microG Companion. They are installed as normal (unprivileged) user apps.

Expected behavior
It should be possible to setup the apps to automatically update; but as the message says, they won't.

Screenshots

System
Android Version: 16
Custom ROM: LineageOS 23.2

Additional context

Reproduce the notice using LineageOS 23.2 with microG Services and microG Companion installed from the microG F-Droid repository. Start by checking the Android build and update settings for both apps, then determine what prevents automatic updates and verify the result through F-Droid.