yup looks like heat stress. i would raise the lights and idk about your grow situation but check humidity as well. for me i have high humidity but i deal with it my own way which might not be suitable for your grow and plus it works best for what i can do/afford but im currently testing out humidity in my grow room and seeing how it affects my plants. Humidity in my state is usually around the 80's it can easily reach 90's in the summer mostly.
with my method though they stopped tacoing but one of the plants the edges are still raise but the other plant it isn't. that plant looks like it is a indica Pheno type though due to the way it is growing where the other seem more sativa dominant pheno. same strains but they are Indica/Sativa hybrid ( mostly indica ) 2 grew like indica's 1 grew like a sativa more taller where the 2 were short and stacked/bushier.