The first is Millenial as a whole, the second is Millenial broken down by age. Essentially, the oldest Millenials have a ~65% homeownership rate and Millenials as a whole have ~54%.
I would have expected them to use the same lines in the 1st chart but change the X axis to be age of the cohort so that they start at the same pt.
It seems like you are saying they got to the 65% rate because it's a snapshot of homeownership % for "older millennials" in 2023. But that doesn't make sense because they also give data for 18 year old millennials.