Why are my pothos leaves like that?

Hi! I'm wondering why my pothos' leaves are curling down like that? They are perfectly fine everywhere else, they get watered regularly and don't have any pests. It is only in front of my grow lights – I thought they might be getting too much light, but the app I use to measure light levels says it's about 300-500 PPFD. The leaves are not limp, in fact the stem where the leaf is connected is very nice and stiff. The roots are also fine, the plants are not rootbound and there's no root rot. Is it getting too much light? Please advise 😭