[...] Yoti automatically flags [...] any devices running GrapheneOS. These instances are automatically reported both to the authorities and our security team.

As I misread the title: the issue doesn't involve any GrapheneOS-specific age verification. It's about a 3rd party verification provider flagging all GraphreneOS users automatically, if you do age verification for other purposes (the reported case was about PlayStation).

It was originally posted in Reddit r/privacy, where it was deleted by mods.

So does it those mean Graphene needs to label itself differently to networks?

Stupid clickbait

Having seen the email, I think this is more just a scare tactic than anything concrete

Is there any way to intentionally fail this attestation with Graphene over and over again by VPNing into the UK with a Graphene device and letting it ban and report you over and over again until detective Nobbleberry from the BBC is in the US breaking down your door?

This doesn't sound real. I would need to see actual evidence posted, not just a "he said she said".

Linux phone users, Yoti is coming for you next