Smog When talking to the JMP.chat people, they seem to believe that the problem is a Graphine OS problem. [...] Could this indeed be a bug somewhere in graphene?
Sure, why not? But it's hard to say.
Most AOSP derivatives (e.g., Lineage) are often very far behind AOSP, while GrapheneOS tracks AOSP very promptly. So if in February of 2025 almost all Cheogram users using Google's OS and Samsung's OS and LineageOS are happy, but there is a problem on GrapheneOS, maybe that means there is a bug in GrapheneOS, or maybe there is a bug in Cheogram that is exposed by the newest AOSP code that almost nobody is running except for GrapheneOS users.
Every time a new Android release rolls out, some developers need to update their apps. Users of Google's OS may update to the new Android over a period of months (and some never will). LineageOS may not update for weeks or months. But a very large fraction of GrapheneOS users will update on the same day. So this forum will fill up with "Why did the new GrapheneOS release break my ThunderTwitch app? It works fine on my friend's phone with the latest BargleOS!!". And app developers may see a sudden wave of complaints "from GrapheneOS users". But really what's happening is complaints from Android 15 users, almost all of whom are running A15 because they are running GrapheneOS.
Anyway, the way to decide whether a bug is in Cheogram or in GrapheneOS is for somebody to find the bug. Then it will likely be clear where it is.
Aside from finding the bug, probably the best thing would be trying Cheogram on vanilla AOSP (which is run by almost nobody). If AOSP and Cheogram disagree, maybe the issue is AOSP, maybe it's Cheogram, but it almost certainty won't be GrapheneOS.