Yeah, it's a bit confusingly worded. A couple paragraphs down it starts to show how the behavior isn't consistent

We verified on a Razr (2026) running an older Smart Feed v2.03.0056 that this does not happen. Our Razr Fold, with app version 2.03.0070, has started showing this behavior, so it’s the latest update that’s to blame for hijacking the user’s intent. We couldn’t replicate this on a Moto G Stylus (2026) running the same app version, though. Sideloading the app, for reasons unclear, doesn’t seem to trigger this behavior, as manually installing the updated version on the aforementioned Razr (2026) didn’t show the same behavior.

Just the fact that the same version installed other ways didn't have the same behavior makes an app compromise conclusion hard to support. But you're entirely right that this could be secondary app caused, potentially the update mechanism on the phone was compromised, which might explain why side loading didn't have the same behavior.