Johnedwardlow It was a incredible coincidence miracle that I happened to flash my phone in the exact precise moment that the problem would've started anyways? I mean, come on, the arrogance to defend such a position. That would literally be like a miracle, lottery win, to be able to time that out so perfectly.
It is rumored that there are around 200,000 GrapheneOS users. With a user pool of that size some odd things will happen to some users. From the perspective of any single user experiencing a single weird thing, that weird thing will seem to contradict years of experience with several phones, also contradict the experience of colleagues with their phones, etc.
But the experience of, say, 50 people with 10 phones each is a lot less than the experience of 200,000 GrapheneOS users for whom GPS works fine. It's also less experience than the non-trivial number of people who flash from the stock OS to GrapheneOS and back to the stock OS and don't report that their GPS broke.
Of course, only you can decide how to weigh the experience of, say, 500 phones among people you know against the collective experience of 200,000 GrapheneOS users.
Meanwhile, if the device is 8 months old and GPS doesn't work under the stock OS, it would seem likely that Google would replace the device under warranty. Google's experience pool involves millions of devices sold per year, so they might find a GPS chip failure to be unsurprising.