My take is that they were trying to block rooted phones and/or custom ROMs of questionable origin and GrapheneOS just became collateral damage because all these companies do go the minimal route of using Play Integrity. GrapheneOS supports remote attestation through AOSP APIs, in fact, they have a page about it.
I think it's worth letting this be heard. GrapheneOS has > 400,000 users and is rapidly growing. Breaking things is not going to affect 5 people anymore, but thousands, ten thousands or hundreds of thousands, depending on what the app is.
There are only bad reasons for them to do that. End users don't get compromised that way in reality, but it does mean they might convince the app to do something that's bad for profits.
GrapheneOS is also not responsible for bugs in this app. Any bug reports coming from GOS are likely to be from the hardening toggles, which uncover bugs in the app. This is the apps fault, and these bugs still exist on other OSs. It should be resolved for the benefit of all users.
"Support" is such an overloaded and vague word in the software industry. What does it mean for a company to "support" an app/os configuration?
1. They deliberately target that app/os configuration, QA tests it, and answer customer support requests about it.
2. They target the configuration, QA tests it, but it's offered without customer support.
3. They target the configuration, but only release an untested build, use at your own risk.
4. They don't target the configuration at all, but the builds they do release happen to work on the configuration, totally unacknowledged by the company.
5. They don't target the configuration, and deliberately sabotage their application such that un-targeted configurations are actively blocked. Only adversarial users who hack the software are able to use it.
Too many companies say: "We can't do 1 because we don't 'support' it, therefore we must do 5!"
About the only time it doesn't work is when the game uses an anticheat system that intentionally blocks Linux. I can even see where the game devs are coming from when it comes to competitive games; cheating ruins the game for other players, and there's no way to prevent certain kinds of cheating without trusting the client to a degree.
I can't see any reasonable and user-respecting place VW could be coming from intentionally blocking access from open systems.
Because of those bug reports, very few may be specific to the non-mainstream OS? https://news.ycombinator.com/item?id=28978086