I am alarmed to see this "damage" and I do not like it!
At first I was thinking insect damage on the underside of the leaf eventually making itself visible on the upper surface of the leaf.
BUT in your last image of the underside of a leaf, between the 2 spikes or inflorescences, those irregular yellowish markings look like it could be a virus! And if it is, that is bad because there is no cure for it.
We have no information as to the light, the temperature and watering details but I am concerned all the same.
