Classic heat stress in those pics.
There are 3 kinds of heat stress- the one from intense, dry heat, one caused by actual light burns, and the one caused by an environment that is overall just too hot n heavy.
The hot n heavy one you will see in a room that is not well ventilated and the low leaves turn yellow, the whole plant loses its perkiness and gloss, and the leaves sort of curl under and droop.
Light burns are easy to spot and can be regular, white, stripes (comes from light burns coupled with a 'hot' diet) or light brown dead crispy patches, with or without curling and deformation, from the plant touching a light bulb.
The stress of high day temps and low humidity makes the cells on the top surface of the leaf lose moisture and shrink, resulting in an upward curling of the leaf margins.