To be fair, since the (magneto clone?) killed her in Grant Morrison's(?) run, she has only come back in the two X-Men: Phoenix Endsong/Warsong mini series, where she's either only alive in spirit or alive in a different dimension. but, while those were canon (since the Stepford cuckoos having the phoenix split into them was used later), she obviously didn't show up when the Phoenix was unleashed in X-Mewn vs Avengers, so she's pretty much completely dead at this point.
Besides that, she's stayed dead. She hasn't actually come back to life as some people seem to claim. I mean, I guess she hasn't stayed as dead as, say, Mar-Vell (who has only come back as a skrull imposter, a ghost during the Fear Itself event along with people like Dr. druid, and a weird clone the kree made and the Avengers met a year or two before Carol danvers stopped being Ms. Marvel who never died, but I think the writers just forgot about him), but she's stayed fairly dead.
I don't count the time travel Jean grey, because she's really nothing like the main one, and I honestly just find her irritating. She's basically a completely different character who happens to share a name and powers.
Wasn't Phoenix Endsong that silliness where they said that now the Phoenix was second to God only in the Marvelverse?
I an SO glad later writers have been trying to undo that.