More of 60s Jean's psychometry.
Side-note...what if Jean's true potential is not necessarily to tap into the Phoenix Force...but the M'Kraan Crystal/White Hot Room/Nexus of Realities itself.
Destiny's precog powers were unable to see Jean on two separate occasions, and she called Jean a nexus of probabilities. Jean was quite separated from the Phoenix at this time, and was before she absorbed Maddie/Phoenix life force...and she was still causing this effect
Jean seemingly had the ability, though not consciously, to mentally transport to the Heroes Reborn reality
After teen Jean "died", the Phoenix was using shards of previous hosts left behind to attack her...eventually Jean is made aware of where she is (WHR) and can actually manipulate it. She then forces the Phoenix to resurrect her.
This could be why she was able to heal the crystal, and is the only host, I think, that we've seen actually operate using the WHR, and what makes her the White Phoenix of the Crown.