Herikusanswered grow question 3 months ago Hey there!
From the looks of it your plants are very healthy and happy. A "lack of nutrients" would present differently in the shape of leaves changing color, curling up/down, etc.
Idk about the heat stress. You provided no information, so I can't really asses this theory.
Also, you seem to have a good quality light and it's not too far away for such vertical growth.
Another theory I have is that due to the limited space in your growing environment and the plethora of plants, they "fight" to absorb as much light as possible. In short, they try to maximize the amount of light absorbed by stretching over one another. Obviously this creates competition between plants and reduces overall yield, because they're more focused on beating each other to the light.
If it's possible, I would think about defoliating so that the light penetrates much deeper into the plant and reduce the "need" to get closer to the light. For your next grow, think about lowering the amount of plants. I know it's awesome to look at the SOG (Sea Of Green), but the overall yield will decrease that way.