The labelling of O2 and H2 on the second stage seems to be reversed in this. Hydrolox engines usually run fuel-rich, and in terms of mixture ratio there's more LO2 by *mass* but more LH2 by *volume*.
Not sure about the provenance of the design for the upper stage illustrated here, but the Ariane 5 and 6 second stage place the LH2 ahead of the LO2 tanks, in approximately the positioning shown here, if the labels were swapped.
