Glo Different issues are described under one thread.
Maybe I missed it, but I didn't see a report (there or here) of a device that exhibited the issue on GrapheneOS but worked fine when flashed back to Google's stock OS. If there is such a case, it might be productive for the GrapheneOS developers to look into it, though probably not very productive if they can't reproduce it. However, if there is not such a case then the issue likely is a hardware problem. Even if it is a firmware glitch that affects a very small number of devices, it's genuinely not likely that the GrapheneOS developers would fix it before Google does, especially if they don't have a device exhibiting the issue.
In terms of moving forward with your device, I can understand that you may be reluctant to factory-reset it or to flash it back to Google's OS. But I am confident that without those steps the likelihood that the issue with your device will be resolved by the GrapheneOS developers is near zero. And if the issue persists after those steps it is extremely unlikely that it will be resolved by the GrapheneOS developers.
Please note that I do not speak for the GrapheneOS project.