This ratio is used to determine appropriate production of lung surfactant, so this baby would not have appropriate production of surfactant if birthed at the time of the ratio calculation. It would go into neonatal respiratory distress syndrome.
TL;DR: surfactant decreases lung recoil, so the lack of surfactant in this baby will cause an increased recoil which will decrease the functional residual capacity (FA 2020 p661-662)
Surfactant is necessary to decrease surface tension of alveoli and increase compliance of the lungs (remember when the lungs have greater compliance, this makes the lungs easier to fill). Surfactant also helps to prevent alveolar collapse as the lack of surfactant allows there to be varying surface tensions between large and small alveoli (Law of Laplace), so lack of surfactant would lead to widespread atelectasis (alveolar collapse). Because surfactant serves to decrease these forces which normally favor collapse of the lung, it also serves to decrease the lung recoil.
Lack of surfactant in a baby = increased alveolar surface tension, lower compliance, more alveolar collapse, more recoil (less residual volumes)
Total lung capacity is unchanged because with enough force you can still expand the lungs to full capacity.
Surfactant deficiency → no reduction of alveolar surface tension → reduced pulmonary unfolding → lungs wont open up → decreased lung compliance and functional residual capacity → hypoxemia and hypercapnia
this should help