It's a preloaded app with possibly privileged permissions (ie. permissions that apps you install normally can't get), so it's possibly worse than what you can normally achieve via physical access. I checked the iVerify report[1], and it doesn't look like such permissions exist, but I'd appreciate more elaboration about the actual vulnerability from grapheneos's debunking post, rather than spending half the article ranting about how various entities are bad.

[1] https://40052983.fs1.hubspotusercontent-na1.net/hubfs/400529...