Had? I'm not sure the newest Pixel has been out long enough for such a big issue to have been fixed. I haven't read about any issues with the P7, though.
I have a Pixel 6 and I've never had any problems with connectivity of any sort. I don't have 5G, though, so maybe that's why? Either way, GrapheneOS uses the same firmware as Stock Pixels use. If there's a firmware problem that Google fixes, GrapheneOS will update phones very quickly. Much faster than other OSs.