Maybe it’s Apple’s equivalent of Guru Meditation.

Maybe Apple typo’d an app id incorrectly for some iOS core app thing in 26.4.2 and the one-character error is this app? I don’t know that anyone’s done a ‘likelihood of collision’ analysis on appstore unique IDs yet. Certainly I could see iOS having a “must be on the device” system set up for apps like Phone and Settings that has a last-ditch of reinstalling it if somehow deleted. Would be especially interesting if some core app that can’t normally be deleted is currently unprotected (back up your device locally first!).

Right, that's what confuses me the most. I was very surprised to find the reddit thread showing that other people are also having this specific app silently installed on their devices.

Headspace leaves health data, that's where my first guess would be