Looks like this is an issue with a a third party update client being confused by a potential misclassification in Microsoft's side about the update (security update vs upgrade).

What I'm most surprised by myself is that there doesn't seem to be an option to revert this according to the comments. I'm pretty sure consumer Windows allows downgrades for upgrades installed in this manner, I can't imagine the pain it'd be to need to manually undo all the damage after an unintended upgrade using automated tooling!