How do you decide when to use the APK versus the split APK?

I am populating a grandchild's phone & one of the first apps I add is
Muntashirakon App Manager which happens to have an APK &  an APKs file.
 <https://github.com/MuntashirAkon/AppManager/releases/tag/v4.0.1>
This is the APK:
 <https://github.com/MuntashirAkon/AppManager/releases/download/v4.0.1/AppManager_v4.0.1.apk>
This is the split APK:
 <https://github.com/MuntashirAkon/AppManager/releases/download/v4.0.1/AppManager_v4.0.1.apks>
I basically know nothing about these split APKs. I admit that.
I'm curious though, which YOU prefer when you have the choice.
What I care about is being able to re-use the APK years later, if
necessary, not so much for this particular app, but for other apps (like
the pulsemsm or nova launcher apps which have last known good versions).
I have to re-use those last known good versions, which sometimes I cull
(aka extract) off my phone. I'm not sure of split APKs play a role there.
Do they?