This is more serious than it sounds. Some users may loose there job, flight or reputation because they miss their appointments when not woken up by the phones alarm clock. GrapheneOS is in good company, though. Apple did the same mistake 5 years ago: https://appleinsider.com/articles/15/10/26/bug-in-apples-overnight-ios-updates-turns-off-iphone-alarms … .
You seem confused about the details of the issue. This is a problem with the Android Open Source Project inherited by GrapheneOS. We applied various bug fixes and improvements from upstream and there were some regressions tied to those. It needs further testing and work on it.