I tried checking both GrapheneOS and Google's issue trackers and I couldn't find this issue in either. I didn't check closed issues in GrapheneOS's, so maybe there was one that was closed as "upstream." I'd be surprised if it wasn't an upstream issue.
Anyway, I ran into the same problem once messing with the settings a long time ago. I'm surprised it hasn't been fixed.
Your post here or a message in the GrapheneOS Matrix room might get attention from a developer, but no, the only "official" place to raise this kind of issue is on Github.