b3nji thanks for trying to help. It's appreciated. I believe this is a bug though.
It may well be a bug. But the question is where/what. If there were a general problem with GrapheneOS on Pixel Folds not being able to read the angle sensor, there would be many reports from users encountering it. And I believe at least one of the GrapheneOS developers has a Fold.
If you do flash back to Google's stock OS and the problem persists, that would be a very strong indication of a hardware problem. However, if the problem does not present on Google's stock OS, I suspect that flashing back to GrapheneOS will also not show the problem (again, because of all the other GrapheneOS Fold users who are not reporting it).
Ranking things from least disruptive to most might look like:
- Clear cache/storage for Launcher
- "Reset app preferences"
- "Factory reset" of GrapheneOS (presumably after backing up data!)
- Flash back to Google's OS
- Flash GrapheneOS again (assuming the problem was not exhibited on Google's OS)
Let us know what you try and what you find out!