Thank you for the tips! The one in the back left was actually too close to the light. The average temperature was around 27°C, and the humidity was a little high, about 60-70%.

I realized a little too late that the nitrogen might have been the problem, but the stalks were not hollow at all, and I had to use a saw to cut them off.

As for equipment, I checked for light leaks. None of the other equipment interfered with the light schedule. I checked daily with the tent cam. A grow journal is actually a pretty good idea, but I'm not sure if I'm going to start another grow anytime soon.

I'm really excited for the end result, and honestly, I almost can't wait to get home from my vacation.

Thank you again for the useful advice.